Personally I like Flashpoint [0] which is a webgame preservation project with a very sizable catalogue of archived Flash games from all over the web + a FOSS launcher app with support for all 3 major desktop OSs in one. It doesn't use Ruffle by default but there is an extension [1] implementing support for it.
[0] https://bluemaxima.org/flashpoint
[1] https://github.com/colin969/FPL-Ruffle