Hi there,
Just wanted to pop in and make it official that I am (and have been for a while) pretty much completely finished with this project. It was mainly an academic exercise to see how well it could work, and, well, it did, though I've long since switched back to using my old Late 2013 MacBook Pro for Apple things. Please don't expect or hold out for anything from me in the way of further insights or answers to any questions, and know that I actually wiped the install clean off my Dell quite a while ago.
Don't get me wrong, I absolutely wish Apple would just say something like "Go ahead and install MacOS on whatever you want, we just only provide support for our own machines" instead of deceptively advertising their own devices and being so absurdly anti-right-to-repair. I mean, just imagine if they had actually said that at any of the past 6 WWDCs--that could've easily been like when Steve Jobs announced the first iPhone. Instead, what we currently have are MacBooks that thermal throttle at stock speeds loaded with weird firmware and bizarre security chips, in addition to a disenchanted professional segment and alienated users. But since when did Apple care about any of those things?
If anything, I hope this serves as proof that Apple really has no excuse to be producing machines that are as under-specced, under-performing, and not-upgradeable as they have been for the past several years (especially at their current prices!!). The 2018 Mac Mini is just barely an exception, but compare it to the PowerMac G4 Cube and the difference is pretty clear.
Anyways, sorry if this is for some reason disappointing to anyone, but I hope it doesn't really come as a surprise. My most recent post in this forum was in December 2017, after all.