1. Fediverse isn't sovereign at all, so the comparison is pretty easy.
2. and 3. You can listen via m3u file. Or query the relays for the kind with a cli tool and retrieve the metadata
There are currently 4 clients:
[https://nostria.app](https://nostria.app/ )
[https://nodecast.xyz](https://nodecast.xyz/ )
[https://sunami.app](https://sunami.app/ )
https://zaptrax.app/
4. Dental care was created by nazi scumbags experimenting on ethnic "minorities". Only you can decide how to draw the lines of guilt by association.