I see plexus mentioned now and then. At best it’s build into the store client. There’s also Sapio (simpler data model though)
I’d love for both to offer regular and licensed data dumps. If the compat ratings are ever built into a store client, a preloaded file saves on lots of network requests.
An app review mechanism by non-Google Android users would go some way, not only compatibility but also foss-app ratings - users miss it.