This is very good news! Please don't forget that even if the great pacific garbage patch doesn't exist, that doesn't mean that the ocean is clean. There are still lots of garbage in the ocean!
However everybody needs to work where the problem originates.
Signal is opensource, but you can't use your fork in the official server. You can use it on your forked server, but then you can't communicate with anyone that's not on your server. So being opensource is just a marketing tool. There's also no way of knowing if the binaries distributed were produced with the source code they published. There's no advantage whatsoever to be opensource for the user. So "opensource" in this case is just a marketing term, like the in case of TiVo.
It will always depend on your requirements. Mapy is from a czech company. They have some cool features (like trips, gpx export, directions, reviews), however if you don't need them, then using a simpler opensource solution might be better for you.
Well, at least i don't gun down people, so i guess i'm not that bad... (i'm at least better than those two)