Last year I tried to get a VGA card for Arduino, like Gameduino. Sadly they are all sold out. The closest thing that I have found was https://www.tindie.com/products/petrohi/geoffs-vt100-termina... which is based on this project https://geoffg.net/terminal.html (already mentioned by other comments).
This is good for text UI but not so good for games. I was thinking about using real 8-bit ISA graphic card, but it turned out they are now considered collector items and have very high prices (at least where I live).
In the end the only sensible choice was to switch to ESP32, there is a module with PS/2 and VGA connectors and audio output I used it to run PCEmulator via FabGL library (https://blog.marcinchwedczuk.pl/fabgl-pcemulator-on-ttgo-vga...), but it is also suitable for programming simple games. Even better you can just put it in a small box with power socket and voila you have a working portable console for 8bit games.
The only problem that I had with this last approach is that you need to do some magic to connect NES controllers to it. I haven't tried it yet, but I was thinking about repurposing PS/2 IO ports.