alternativeto.net
Use this site and look for the "Open source" tag and double check the source code is available on every piece of software you find.
I've found that they commonly mislabel apps as FLOSS when they are actually proprietary. That being said, I only ever used it for more niche programs, so maybe common programs are more accurate.
For what platform?
TempleOS?
Biebian?
android, sorry
YouTube: New Pipe
Maps: OSMand~
Both from FDroid (the former you will want to install their own repo)
For maps: either OsmAnd or Organic Maps. The first one is a beast but needs to be tamed, the latter one is more user friendly. They are both based on !openstreetmap@lemmy.ml
Additionally, you can use https://mapcomplete.org to improve the maps (or the online editor in openstreetmap.org)
All about open source! Feel free to ask questions, and share news, and interesting stuff!
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