I have no experience with android apps and just started working on one that needs to work with relational data. The relational data has multiple many-to-many relationships and the inbuilt ORM (Room) is leads to class explosion.

While looking at ORM libraries for android, there seem to be many that are out of date:

From 5 of the Best Android ORMs (2014) and AlexeyZatsepin/Android-ORM-benchmark (2017)

• ORMLite: 3 years old and the M2M example makes me feel quite queasy
• SugarORM: description explicitly only mentions 1:1, 1:n
• GreenDAO is unmaintained but replaced by ObjectBox which I haven't yet looked at
• Active Android: abandoned
• Realm redirects to MongoDB 💀
• Freezer: abandoned
• DBFlow: no documentation and 3 seemingly abandoned
• Requery: 4 years old (abandoned?). Actually my favorite in terms of API
• Sprinkles: 10 years old, dead

I'm leaning towards Requery because I like its API the most (hides SQL the most), but haven't looked at ObjectBox yet.