I wish all of this angst could be bottled up and used to create a simply workable version of GNUstep --- ideally targeting something easy to configure hardware-wise like a Raspberry Pi 5.

I agree.

It's not really what you're asking, but I know of two Linux desktops that are based around GNUSTEP.

NEXTSPACE:

https://github.com/trunkmaster/nextspace

-- primarily targets CentOS

GSDE:

https://onflapp.github.io/gs-desktop/index.html

-- primarily targets Debian