You say that but it’s a one year old play form and protocol, of course it is just Bluesky. The Fediverse existed long before Mastodon and Mastodon is 8 years old, so I don’t get your point. That still doesn’t touch upon the negative to tethering users identity to instances. Many of them have tried Mastodon and it was a poor experience for them. So, it’s not an option. The Fediverse isn’t for everyone and that is absolutely okay. People are hoping to leave and not use Twitter/X, they have good alternatives that suits their needs and that should be celebrated.
I don’t think there’s currently any platforms that do that but depending on what mobile and computing OS you use there’s client option