RISC PC systems are still a supported (tier 2) platform in NetBSD. You should be able to cross-compile the whole system including X11 from any Linux or NetBSD host (I did this last week for the next68k port) and the developers would certainly be happy about feedback before the 11.0 release is published. So this might be worth giving a try.
https://wiki.netbsd.org/ports/acorn32/
https://www.netbsd.org/docs/guide/en/chap-build.html
Not everything is working in NetBSD all the time. When testing the “previous” NeXT emulator, we faced some nasty regressions last year that prevented NetBSD 10 (and, as we found out, every release after 5.2.3!) to run on next68k, but things were fixed eventually thanks to the nice and friendly next 68k platform maintainer!