We have to go back to the meaning of the term existence. As I have said in previous answers existence has an interesting history which has to do with the collision between Greek which is a language like all other Indo-European languages that have Being and one of the other myriad languages that do not have Being, but instead have either existence, or copula or something else which plays a similar role to Being as the central concept that relates things to other things. In this case the language was Arabic, and the Arabs were reading Greek Philosophy and realized that Being (ontos) in Greek was completely different from Existence (Wajud) in Arabic. So the Arab philosophers made up a technical term Kun (to make) to specify the difference between Being and Existence. Then during the Renaissance when Arab interpretations of Greek philosophy were translated into Latin there was no term for Existence in Latin which was an Indo-European language to, so the term Existence was made up to have the same meaning as Wajud in Arabic which means “that which is found” and also ecstasy. Heidegger uses this difference in senses of existence in Being and Time when he says that the projection of Being by dasein is an ecstasy. Existence means Exi-Stance, to stand outside of . . . Being. It is what is outside of our projection of Being, i.e. what comes before the Apriori Synthetic in Kant’s terms. Existence is what is found prior to any projections of ours onto what is there such as values for instance. So the rock beside the road that no one cares about has mere existence.
Now when we talk about True Existence then another aspect is revealed. What is interesting is that both Being and Existence are standings that share the aspects Truth, Reality, Identity and Presence. Thus in some sense aspects of Being and Existence are more fundamental than the standings themselves. So when you say True Existence, you are really talking about Existence without any contamination with the illusion generated as a projection a prior in Being. But also we could talk about Real Existence, Identical Existence, and Present Existence. In existence these different aspects are not separate from each other as they are in Being. That is a difference between Being and Existence. In Being the aspects are separated but in Existence they are interpenetrated.
The opposite of the Existence I call the Quintessence. The Quintessence is both aspect and anti-aspect, while Existence is neither aspect nor anti-Aspect. So the Quintessence is both True and False (Fiction) while Existence is neither True nor False (Fiction) and so on with the other three aspects. The main interpretations of Existence are Buddhist emptiness or Taoist void. That is to say Existence is interpreted as non-dual. In this interpretation it is not non-being and neither aspect nor anti-aspect but instead NOT (Aspect) nor (anti-aspect), nor (both aspect and anti-aspect) nor (neither aspect nor anti-aspect) but something else beyond these logical alternatives. That something else is interpreted as interpenetration which is the antipode beyond existence and quintessence. An image of the quintessence is the philosopher’s stone, i.e. the perfect transformative catalyst that in myth turns base metals into gold.
Now the model of Existence is the Special Systems and the Special Systems are interleaved with the Kinds of Being, so Being and Existence are duals of each other. The Special Systems are a model of interpenetration (cf Reflexive Autopoietic Dissipative Special Systems Theory of the author http://kdp.me). And the special systems describe the ultra efficaciousness of Life Consciousness and the Social. So in this sense the viability of just living is true existence. Doing something “productive” with your life is part of the projection of Being. And so from the point of view of this sort of Fundamental Ontology/Existentialism, existence covers life, consciousness, and sociality, but does not cover Productivity, which is part of the projection of illusion and delusion of Being. The best book about this is the Mirror of Production by Baudrillard where he says that what communism and capitalism share is the idea that we must be productive, to be human is to be productive, and what cannot be imagined is an unproductive life. However, Buddhism and Taoism and other non-dual spiritual ways undermine this assumption of the preeminence of productivity in human life and say it is enough just to be conscious and to recognize the purity of existence unsullied by the projections of Illusion that are founded in Being.
Thus I would answer the question you raised by saying that the true meaning of existence is in just viable living, purified conscious, positive and non-destructive social relations, and productivity is a delusion (like “Progress” for instance) which according to the Buddhists and Taoists would be based in delusion.
However, this said I do find that there is a big difference between the productive life and the non-productive life myself. And we must realize that productive and destructive are duals. Nietzsche says that all creation is based on destruction. So that productivity and destruction are intertwined as nihilistic duals that feed each other. So the nondual of existence has to be between and beyond these duals as it is with all duals. Thus it has to be a misinterpretation to say that the Buddhist or Taoist life is completely non-productive, but on the other hand it is not productive either. The difference is that in these contemplative kinds of life what we are trying to do is to produce a transformed self, so that our productivity is aimed back at our selves not at other things in existence. Zen/Chan aesthetic traditions make much of this in arts of Flower Arrangement, Archery, Gardening, Tea Ceremony, Calligraphy, etc. In other words, there is a certain attitude toward work, which all Zen monks are required to do, which does not focus on the end product but the consciousness of what is happening in the process of creation or production in the moment. An excellent example of this is the poems of StoneHouse (translated by Red Pine), where he criticizes the buddhist monks for begging, and prises the hermit who makes his own food or gathers it, or works gathering fire wood and is not dependent on the generosity of others for their livelihood. His poems are the perfect example of the blending of Taoism and Buddhism. In fact at a certain point in his poems he has a line of emptiness and a line of void, then a line of emptiness and a line of void. Much of Korean Zen comes from the StoneHouse lineage which combines Zen and Taoism while recognizing the difference between emptiness and void as two different attitudes toward existence. In Taoism there is the idea of “non-action” which does not mean not doing anything, but means not fabricating anything nor departing from the natural flow of nature which is he Way (Tao). In Taoism non-action may mean producing something or not producing something depending on the situation. The basic idea is that you remain unattached to production or non-production. But the emphasis in production or non-production is on the transformation of the self not the transformation of external products as it is in capitalism or communism which assumes that productivity/destructivity is a basic human trait.