Hey; just struggling with something - How do I make it so that the nether inherits the main survival world's permissions?

A group should have permissions in all worlds by default, as long as you don't set any world-context to it.

I'm not sure, if I really understand, what you want (and would be happy, if you could explain it a bit more and maybe with one or two examples).

https://github.com/lucko/LuckPerms/wiki/Configuration#world-rewrite