Thanks everyone for all your positive comments and feedback, I was not expecting this much attention. Sorry for the problems with browser compatibility, the simulation kernel needs thread support, and this is fairly recent in WebAssembly.
I started this last April and spent many evenings tinkering away "on my project". Trying to chase Ben Eaters 6502 series as he released new videos each month or so gave me the motivation to try to catch him up with my digital twin version. I guess I was thinking it'd be cool to allow anyone to follow Ben's project armed only with another browser tab sitting alongside youtube.
Many thanks to all the authors of the OSS I've used, especially Dear ImGui, ImGuiColorTextEdit, cc65 & floooh/chips headers. The whole thing is done in C/C++ and I build and debug natively on a Raspberry Pi with Visual Code gcc/g++ before running through Emscripten and uploading to the web. SystemC is the simulation engine, the hardware models include a bit of timing to try to get close to the physical hardware behavior. I wrapped SystemC around the floooh/chips.