I've been playing with the idea of creating a "protobuf db" library that would allow you define schemas in protobuf and then query them with something akin to an ORM. It wouldn't make any sense for large databases, but for embedded applications that only need to store a few MB of data, it would be perfect.
I've been working on a separate branch, which finally builds (there were 1100+ errors), but I'm still working through iOS/macOS build things for it before merging it to main. (I've sadly had to abandon the Android build, because Google Play was a comparative pain, and FluidSynth upstream kept breaking the Android build I set up for them. But I'm reviving the project for iOS, macOS, and web at least.)
Here's the branch: https://github.com/JonLatane/BeatFlutter/tree/update-to-late...