Tube Time has done many things, you can follow him on Twitter or Mastodon, and his github is a gold mine, notably :

• EGAMemory his last project : a 192 Kb of RAM for a 64 Kb EGA card so you can get EGA high resolution (for a PC 1640 you needed the ECD monitor, the CD monitor was only low EGA resolution, whereas the MD monitor was only MDA and Hercules)
• Quapple, a clone of the Quadlink card sold in the past to run Apple 2 programs in your PC with an ISA card (see this video on Youtube testing the card)
• The Graphics Gremlin : an ISA retro video card using a FGPA which supports MDA and CGA with a VGA output and the original video port
• The Snark Barker : a clone of the Sound Blaster 1.0 (with CMS support)
• Orchid Tiny Turbo 286 Accelerator Card : a clone of the original card transforming your PC XT in a PC AT with a 80286. This isn't the only card who existed. There is also the Microsoft Mach 20 Performance Enhancement System (1988) or the card by Intel (first link and second link) which adds a 80386. The first page on Dos Days mentions other accelerators)