Blokada - this app runs in the background as a vpn client and blocks trackers and ads that irritate us all over. You may still see few ads in apps like Youtube because Google does an end-to-end encryption for serving ads. See next app to solve this.

NewPipe - this is an alternative and a much better app for Youtube. You can download video or only the audio. You can subscribe to channels without Google or Youtube account. No ads. No tracking. A clean video experience. Video popup modes, etc.,

Fedilab - I have already written about it. My goto app for accessing Fediverse.

OsmAnd~ - Completely offline Map viewing and routing application. The data comes from @openstreetmap First time download of map is required. You can record your trips and export them as GPX file and share it with friends, add places to the map, contribute to OpenStreetMap like Wikipedia, etc.,

CityZen - another OpenStreetMap based app for exploring various avenues in a city.

StreetComplete - Like a game, it shows you what information is missing in a particular road or street in OpenStreetMap, so you can start contributing to OSM in a more fun way. With OSMGeoWeek around the corner, it’s good time to start.