The Faxanadu multiworld randomizer uses a modified fork of FCEUX to build its own supporting interface and... gods... I need people to understand LuaCanvas exists and you can just do this without having to fork an entire other emulator or writing a weird sidecar memory scraping UI.
It's mostly/entirely a Bizhawk thing yes but so is the crowdcontrol library everyone uses for AP hooks anyway.
@elfi I've been there. When I did 4-5 Four Job Fiesta runs a year I had an interface that used Lua to probe memory addresses, write them out to a pipe, and then a Python widget to read that pipe and draw the pretty stats interface.
Then I learned LuaCanvas exists when Facet asked vee if it was possible to make Other Interface Things for a gimmick they wanted to do and I was enlightened.