I always say that one of the problems in the Canonical's strategy with Snap is not to provide the backend allowing everyone to set their own "store". Then, Canonical would focus in the added value of their one, with things such as a payment processor, malware scanning, ci/cd integration, stats, etc making it appealing.

Flatpak allows this, but, in the other hand, despite I exclusively use Flatpak these days, I dislike the fact that is not focused in CLI apps but desktop ones instead.