1 Hello, I guess. Is this the tech thread for tonight/this morning?
(When you're working the night shift/night watch "today" kind of becomes a strange concept. "Tonight" is the 22nd. And the 23rd.)

2 "If you do keep using a Skyline into the Android 16 era, you may need to root it yourself and install a replacement OS, which is far beyond the abilities of most end users. We have also yet to see any confirmation from HMD that it will provide any assistance with unlocking the device's bootloader."
Probably the biggest thing that would hold back users from using custom roms is that the people who write them aren't really good at writing clear, easy-to-follow instructions.  There's a lot of "oh, 3 steps back, if x doesn't work, do y".  I used to play around a lot with custom ROM installations until Samsung added Knox to their phones and made it harder.
Not being clear about how to unlock the bootloader is troublesome, too, although sometimes it's as easy as flipping a toggle in the Developer options (and being OK with that potentially burning a fuse so that you can't undo your changes and put a stock ROM back.  This really only matters if you're using apps that refuse to run when that happens, like (IIRC) Netflix and some banking apps.  But that's not a documentation issue.)