On android - yes.

Specifically I would sideload fdroid, and then install (free) apps from there since it doesn't need a login.

Or maybe I'd (say, on windows) "sideload" steam, and install apps from there instead of from Oculus.

The idea that the only place I can get apps from is the "official" appstore is ridiculous.

This wouldn't change if it were a store account instead of a device account. Most people use google's play store but this doesn't mean every android device needs a mandatory google account.