That's currently a gap for small boards. The ALIX boards have been the x86/32 bit answer for a while: https://www.pcengines.ch/alix.htm

I haven't seen a 64 bit solution that stayed relevant yet. Intel's Edison was the big contender, but has since died[1].

Gutting an ASUS Chromebox is a decent and cheap interim solution. They are well built, reliable, available, and cheap. Basically a subsidized Intel NUC.

[1]https://hackaday.com/2017/06/19/intel-discontinues-joule-gal...