It seems to me like ease of use and user 'sovereignty' are on a slider, Nostr certainly leaned hard towards the latter. Not that I don't like a good cipher punk protocol, but easy onboarding is not its strong point.

At least the outbox model fixed the relay issues though. Fetching users posts from the relays they set, as opposed to the relays you use, did a big jump towards fixing relay issues. Though not all clients support the outbox model as of yet.

Is there actually a list of clients that support outbox?

I only really use Amythest, which I know supports it. There's probably more, but I'm not sure of any lists of clients that have implemented it yet.