No idea on iOS, specifically left the OS due to its lack of interoperability.
On Android I did test but https://f-droid.org/en/packages/com.atharok.screentime/ or https://f-droid.org/en/packages/godau.fynn.usagedirect/ looks like good candidate. I’m not sure if they have export or publish to API functions but I image at this point would be relatively easy to add.


I believe the idea is that you run your own instance if none of the existing one fits your need.
If you do set one up for LUGs you can, if you want, decide to then open it up for LUGs organizers elsewhere.