As of the time when I wrote this reply, PB2 in Ruffle Flash Player works but has some quirks.
The preloader marine animation doesn't work, the 3D main menu doesn't work (except buttons), but major things like multiplayer works (if it ever disallows Ruffle Flash Player in multiplayer in the future, feel free to let me know).
https://ruffle.rs/downloadsYou can download the latest version there, browser extension or standalone, your choice.
You can also report issues to Ruffle's GitHub
https://github.com/ruffle-rs/ruffle/issues/new/choose.
In this case, it's for PB2, choose bug report if you find anything missing in the game.
If it's a crash that you somehow encountered in PB2, choose crash report.
Ruffle's slow in PB2 but for some other games it might run fine, but can we put it in the PB2 website? Probably not.
(nerd time starts here)
The more better option would be to port it to HTML5, which requires knowledge of the PB2 flash source code and how to execute it well, if it's not executed well enough then people will complain about missing PB2 flash stuff in PB2 HTML5, which Eric definitely doesn't want. Porting to HTML5 has some benefits that completely defeats Flash entirely (well not entirely, you can put negative thickness to text).
A 1:1 recreation of PB2's texts and menus of the original is almost possible in HTML5 but at least we know it's possible to port PB2 to HTML5.