I've thoroughly enjoyed Tree of Woe, and I had some good conversations with the author about this topic in a private chat.

My only quibble with your proposed "megatheism" is that it might erase some philosophically important differences (or at least, arguably important). For example, my understanding of late Platonic thought, such as that of Plotinus, is that "the One" is emphatically not "a person" in the sense that Gods are usually conceived as, and as the "God Most High" of the Hypsistarians and God the Father of the Jews and Christians definitely is. Of course, my understanding may be off, or it may be less of an important difference than it seems, but that's been my main sticking point with folks who offer something in the "megatheistic" camp.

Related, but if you haven't seen the "Physiocratic Curriculum" series of posts with recommended reading, they're quite good, and I especially recommend the metaphysics one for some further insight into where he's coming from and why he found the Hypsistarians so compelling: https://treeofwoe.substack.com/p/recommended-reading-part-iv-metaphysics