What is left? Any recommendations for a modern-day receiver for two-zone 5.1.2 and a 2.1 setup?

Get the denon x1800 while it’s still available and you’ll have to worry about this question in 2035… come to think about it, maybe get two.

There’s always Sony too, who still put out pretty good receivers.

Minidsp flex ht or htx paired with a buckeye 6 channel amp. As cheap as you can get premium sound quality. Not cheap but you get the software control you actually want via the minidsp

I like Yamaha.

eBay. Plenty of excellent vintage un-shittified sound equipment for sale. You may need to re-cap the amplifiers, but the speakers should still sound perfect.