I'd love to be able to use this outside of the WPLMS theme as well. Is it possible to tweak the code so that the "settings" are available somewhere other than inside the LMS plugin? Like under the Wordpress "Settings" menu?
The LMS settings doesn't come from wplms theme, it comes from the vibe customtypes plugin.
So to use wplms S3 outside wplms theme, you can activate vibe customtypes plugin and make the settings accordingly and use wplms S3 plugin on that setup.
PS: I have not tested this but it should work fine with vibe customtypes plugin.