Both of these services appear to be dependent on BlueSky. I.e., if BlueSky ceased existing, or cut them off from its API, they’d die.

One could theoretically make one’s own independent AT Protocol network, but not in a way that interoperates with BlueSky as a peer. You’re either a subsidiary part of its network or you don’t exist as far as it’s concerned, which is a much poorer value proposition than ActivityPub and related protocols.