buzzard.2 is a classic: https://www.ioccc.org/years.html#1992 Despite being an entry to a competition, the code itself is actually barely obfuscated, just very terse, and it comes with pretty good design docs.
Stack machines and forth are rather good in general. I started by reading https://users.ece.cmu.edu/~koopman/stack_computers/ and then found https://forthworks.com/retro/ which vm is very pleasant to look at and has interesting assembler. You can also try looking at https://wiki.xxiivv.com/site/uxn.html For something more high level, I myself am currently eyeing Urbit. Though, there's plenty of crypto/NFT cultism, their core stuff is not really developer friendly, and I don't like how their VM reimplements half of the standard C library, so I wouldn't really endorse it. >preferred non lisp, supporting infix notation Eeeh, prefix/postfix notation makes things so much easier. Just embrace it.