I think about this alot. It's a weird problem because free and open source doesn't mean you can't profit from it. It's arguably the other way around. You're supposed to contribute so the market services are the value add to your platform. A marketplace is the answer for this servicing problem but it can't be free because then the consumers are the product.

I feel like the solution is to build the marketplace platform technology INTO Godot so then developers can target the platform and the service providers are then able to provide the same product with their own partners and value. This would create competition in the space but allow for growth in development.

I think this is what flatkpaks are trying to achieve with remotes like flathub. It's just supposed to be one of many marketplaces but the marketplace technology has been standardized unlike the snapstore. This also prevents platform lock in.

The technology then remains free but service providers need to be able to derive value from the hosting as hosting costs money no matter the platform. The consumer can then drive the demand.

Of course lock-in is the goal of all service providers... So there's that ...