People do want alternatives. Bluesky is a clear example of that. Nostr is clearly not as big, but it's a protocol.
Only if you're on a Bluesky-operated PDS. That's straightforward to fix, at which point the most Bluesky can do to “ban” you is stick a label on your account that non-Bluesky applications/clients are free to ignore.
> to my knowledge their promises of being decentralized are comparable to Telegram being E2E encrypted.
AFAICT your knowledge is about a year out of date.