Here's a video about the PicoMEM, another Pico-based ISA card project similar to PicoGUS, except it focuses on memory expansion and disk drive emulation. It can expand conventional memory, add EMS memory, and replace XTIDE for hard drives and Gotek for floppies. If you saw my booth at #VCFMW, I had one running there. It's not a "finished" project but can already do a lot! 
https://www.youtube.com/watch?v=urBkxpwz69Q