I checked right now and I’m logged in and I think it’s necessary to contribute. But it’s a simple form to register and you should try. It’s pretty addictive to answer questions about your surroundings :)

Komoot - great bike route planner and gpx recorder.

Mapy.cz - great hiking navigation with trails colors/indications. Mosty Europe I guess.

Fdroid ->Catima - simple loyalty cards / barcodes instead of supermarket apps

Fdroid -> StreetComplete very easy contributing to osmMaps. You know your neighbourhood? Answer questions if that trafic lights have sound indication for blind people or about the type of surface that bike line has.