The elephant in the room here is how you ethically get people to onboard without an existing community / fomo / money.

The trick is getting the content creators there, but most of them are ultimately and fairly interested in making money, and your new platform wont have that for them.

Bluesky has done alright, but that was a black swan event Elon Musk inspired.

Do what reddit did, use multiple accounts as founders, and with AI I'm sure it's even easier to do so. For content-based platforms you must have content, there is no way around it and I don't see adding fake content in the beginning to be unethical, it is a solution to the cold start problem (also a good book by Andrew Chen at a16z [0]).

[0] https://a16z.com/books/the-cold-start-problem/