No, they can't. The fediverse doesn't work like that, it isn't controlled by one entity, the most individual instances could do is defederate from Reddit.

To convert that to open services: Let me just post this on Pixelfed, send it via Telegram/Signal, upload it to (hmm, can someone help me here) and have it recompressed by Odysee/Peertube!

The difference is that you can't choose your skin color, but you can't choose your beliefs in a different way.