Universal Radio Hacker probably isn't as simple as you are hoping, but it should be moderately easy and very powerful https://github.com/jopohl/urh

You can listen to FM radio with gqrx relatively easily, if you can navigate through hundreds of input boxes.

sudo apt-get install gqrx

Anything more complicated will require some coding knowledge, unless someone already created a library for that specific thing.

There is also a ready-made package to listen to GPS signal, unfortunately it needs an external amplifier and a proper antenna, because RTL-SDR is not sensitive enough for GPS.