There is a white noise generator, which "cat /dev/urandom | /dev/audio" or a couple of lines of C code will accomplish. With just a few controls you can tailor the spectrum easily.
Then there is an "ambient music generator" which you can knock together in a few hours with Csound, Supercollider, Pd, Chuck/Faust and the like.
Then there's an "ambient music application" which in addition to inbuilt generators works with with online libraries of generators, seeds, patterns, sample loops, and a package/element manager for getting and adding "songs". Last time I built one of those it was a few weeks of effort.
Then there's getting all that to run on smartphone, on multiple platforms, getting around all the quirks, permissions and general madness that is phone dev ecosystem.
Well done on that last point. Seems the last of these is what the author has created and I kinda think it deserves a better name than "white noise generator".
I didn't realise there is still quite a culture of "noise generators" for people wanting to sleep, read or meditate.