@tchambers
You can see here what apps support the tag:
https://podcastindex.org/apps?elements=Social+Interact
If you mean as a podcast player:
AntennaPod: Has a button that open the SI link (basic implementation), it's hidden on the 3 dots when you are playing the episode. (PR sent @dave I thought this was already declared https://github.com/Podcastindex-org/web-ui/pull/496)
CC @keunes
Podverse: Old version used to show comments on episode page, not sure if that works any more. Next version it's probably going to support it. CC @podverse
https://podverse.fm/es/episode/YPUx7sbco
TrueFans: Better integration so far, you can see comments, and TF propagate and uses ActivityPub. CC @samsethi
https://truefans.fm/kde-express/691dbac132a52171c604d877?tab=boosts
Up Next: It's FLOSS but for iOS so haven't test it
https://extremelysuccessfulapps.com/up-next/
CC @jtrentadams @adam @james @js