IAP in a game that has not been released on the Oculus Store?

I'm currently developing a game with a target of Oculus Quest. Based on the experiences of others' that I've read I have every expectation that I won't get accepted on the Quest store. So I'd like to develop with the full expectation that I don't. Is it possible to put IAP in a game without being officially listed on the Oculus store?

I'd expect people would be able to sideload the game via sidequest, I'm happy to give the game away for free, but I'd like the ability to have some ingame options just in case. It's not a core pillar of the game and I'm a sole developer so I certainly don't want to be writing a payment processing gateway or worrying about the security and overheads related to all of that, but I'd love to plug into a gateway.

Is this a pipe dream?