Indeed. I'd happily pay Reddit directly for an API key if that let me run RIF in a "bring your own key" mode. They could split the profits between themselves and app dev. I'm surprised no one is proposing this. But I guess this comes down to people willing and able to pay to avoid adtech cancer being actually the most profitable cohort for the advertisers...
this is explicitly blocked by TOS. You can notionally do it by taking a "RedditIsFun" APK and injecting your own API key and then sideloading, but they'll do app store takedowns for any third-party app that supports it natively (because it's a TOS violation).