I actually don't think you need to put a lot of effort in order to make Flash usable in a browser. Just get Adobe Flash 32.0.0.363 from Internet Archive (clear net only) and Basilisk Browser (clear net only). Sure, Adobe made Flash dead since 12 January 2021, Mozilla will fully kill Flash after 7 September 2021, Google made Flash dead since 19 January 2021, Microsoft released a Flash-killing update on 18 February 2021, Apple was the earliest to kill Flash on 16 September 2020, so using Flash has been made more difficult, but it's still not impossible!

And actually, if you know how Microsoft earns money, then I guess it's fine?