Why not..
1. User installs 3rd party app
2. You accept reddit TOS, an API key is attached to your account. It could even be integrated into apple/android keys or user subscription models. You pay either directly to reddit or via your payments to the 3rd party app service fees
This could work for so many use cases. Why should developers need to do think about all this nonsense like key rotation, constantly changing pricing models, using round robin API key rotation because you're hitting limits with one key, etc. Devs should just set up the experience so users can bring their own battery and plug in to start playing.
Just provide the backend. Let devs build cool 3rd party apps around it. Each user can just get their own API key that's tied to them, either simple case like the reddit account, or its part of the apple id subscriptions + keychain.
Everyone makes money. Everyone gets to learn programming or whatever the fuck makes them make 3rd party experiences. Everyone can just be happy.