Btw there is this (commercial) tool that turns Flash to webassembly.
What they actually do is they run whole Linux (!!) in VM in webassembly, then they run the officially licensed Adobe Flash player there (and you need a separate license for that from... Harman? as those now own Flash IP).
https://labs.leaningtech.com/cheerpx/for-flash
(I'm not affiliated with them in any way. Just found it interesting one day.)