> https://c256foenix.com/ Based on 65c816, affordable, powerful and - most important - already available and well tested.

I went to the link:

Available: it's all sold out. Admittedly, it exists more than the project of this post, which was announced 2 years ago and still has to deliver.

Affordable: disputable, this is priced $220/$260 for a bare board (no power supply, no case) so you can find cheaper Amiga/ST FPGA boards; but it is not ridiculously expensive either and some of those Amiga/ST boards are unavailable too.