The problem isn't stripping away the religious BS, of where there are indeed plenty, its the fact that you never even engaged in the standard practice of Daoist or Buddhist meditation nor engaged in even the superficial aspect of the actual philosophy of Mahayana Buddhism to even be qualified to comment and strip away what can be deemed mystic nonsense. You simply denounce the doctrine without even entering, let alone understanding the basics. I've started out with a materialism deterministic attitude long ago (so you are doing nothing unique), also not understanding what Buddhists meant by emptiness and mind only, but once I read deeper into Yogacara, Madhyamaka, and Huayan discourses and their commentaries, I realized Buddhist mind only has nothing to do with denouncing material reality's conventional existence nor is it anything similar to western solipsism based idealism. Buddhist philosophy is light years more intricate than Daoist ones (something even Tang emperors like Taizong who claimed to be descended from Laozi, recognized) and also answers questions not answered in Western idealism. I still don't believe in any of the religious cosmologies mentioned in Buddhism like the purelands, but Buddhist philosophy is a whole nother animal.Of all the Original ancient beliefs, only TWO, in my view, have stood the test of challenge and modern science without being proven erroneous. The original texts of Taoism by Lao Tzu and Chuang Tsu. And Stoicism as elucidated by Zeno and Epicurus.
Neither bothers itself with any form of "afterlife" . Rather they seek to understand Life and being as we Can know it.
Strip away the malarky in other ancient traditions- such as the supremely complex Hindu mythology, and you find much the same basic insights into perception and being in most of them.
But my argument is that if you really want to get what is of value out of ancient philosophy or mysticism... you really have to try and tear away all the generations of false embroidery and facade that people who really did not understand it laminated on top.
Yogacara philosophy isn't just some outdated ancient philosophy, it has been deemed superior to modern Western idealism and epistemology by a number of modern Eastern philosophers. If you knew a thing about the doctrine, you'll know that everything you experience in the meditation of insight (Vipassana) is this worldly. Emptiness is not some transcendental mysticism, its seeing the world without self nature and conceptual trappings.
Also from your description of meditation, I know you never even tried any of the current central Daoist or Buddhist meditations. The very nature of insight meditation is to see the emptiness of phenomenon and detach your thoughts from objects, and clinging on to materialistic determinism is one of the biggest obstacles (if not outright contradictory) in such meditation. Even Zhuangzi talks about meditations similar to Buddhist insight meditation, Nan Huaijing relates it to Xinzhai 心斋 or "fastening the mind".
"Yanhui asked, what is fastening the mind? Zhongni answered: if one is of one determination, not listening with the ear, but with the mind; not with the mind, but with the breath. The listening stops at the ear, the mind stops with the image." Zhuangzi, chapter 4
Early Zen never focused on the afterlife, in fact several masters would outright hit students if they make metaphysical speculations of what happens after death; not because they believed in materialistic nihilism but because the idea of a self dying is another samsaric conceptual delusion. Even the early Buddhism mentioned in Pali and Agama have Buddha refusing to answer questions such as what happens after a person achieves Nibbana and then dies.