Check out this website. It has a ton of different natural soundscapes (some only accessible to donors though; one time donation), all of which can be independently configured to your liking, and there's a button that makes the sliders randomly change over time too.
Thanks, but I found it simpler to simply use youtube-dl to download the audio component of a bunch of videos and and do an "mpg123 *" in a background window.
https://mynoise.net/NoiseMachines/rainyRiverbankSoundscapeGe...