I'd like to recommend a website I've been using for a very long time - mynoise.net - which seems to have exactly what you're looking for [0]. There are many different kinds of ambient noises you can play indefinitely, and there are even sliders you can use to compose your own "mix" of ambient sounds of a particular type (e.g. Wind Trees, Distand Stream, Close Stream, Owl, Birds, etc.).

There are many types of ambient sounds (I count 100 at the moment) available for free, and even more if you choose to donate to the site. You can donate any amount you want, and you get lifetime premium access to full site content.

The guy running the site, Stéphane Pigeon, is a signal processing PhD with a passion for sounds, and he travels the world recording ambient sounds for this website.

[0] https://mynoise.net/NoiseMachines/belgianForestSoundscapeGen...