I built this type of system for nostrocket about 6 months ago as an example business model, but didn't deploy it because I got side tracked and also began to view relays as just a cost center for a different business model.

Maybe I'll get back into it after Atlantis.

Customers who pay for access to the relay pool are paying directly to the relay rocket's "shareholders" (non custodial).

To get shares, you do work. Some of that work is developer stuff, some is paying for a VPS and managing a deployment etc.

Relay deployments are all using the same corebase and take an access control list from the rocket.

This means that the rocket can spin up/down relays as required (cyclical demand, geographical region, etc)