Given the US recently made a bid to fast-track multiple censorship bills, KOSA included, and is also trying to kill Section 230 now, which will pose an existential threat to Fediverse instances hosted over the clearnet, how feasible would it be to host said instances over Tor/I2P?
Yes, it is feasible and such instances already exist.
For example, you can run a Mitra instance on Tor, I2P or Yggdrasil. It is a lightweight micro-blogging server similar to Mastodon:
https://codeberg.org/silverpill/mitra
Tor / I2P docs:
- https://codeberg.org/silverpill/mitra/src/branch/main/docs/onion.md
- https://codeberg.org/silverpill/mitra/src/branch/main/docs/i2p.md