[energy123]

I'd like this but with pleasant sounds

[intelkishan]

There’s https://mynoise.net for a variety of ambient sounds

[PunchyHamster]

just search for ambient noise generator, there are bunch of them

[reaperducer]

The iPhone comes with a bunch built in.

https://support.apple.com/en-us/109346

[JSR_FDED]

Thanks! That page also refers to some Apple Musix playlists that are excellent for sleep, relaxation, focus.