For my uses there is always too much additional nonsense with noise apps. Here's 5 lines of Faust that satisfies all my noise requirements (a noise generator and a lp filter with simple UI) you can export as ab android app or to various other platforms: https://faustide.grame.fr/?autorun=1&voices=0&name=exfaust0&...
Examples: type sleep noise into the android Play store and the top few. Waves, bird noises, rain etc. All useless to me - just want masking noise to block other stuff out.
I use so-called analog or mechanical sound machines like the Marpac or Yogasleep Dohm, so not much use for other noise generation stuff. But every now and then I use an app when I don't have my machines, which I sometimes travel with.
Do you have examples? I have been decently happy when I have needed to find one, even free ones.
Your link doesn't play and also requests access to my microphone.