I think a procedural generated space opera is a bit difficult to do.

Space operas are closer to fantasy than hard science fiction: they are about extraordinary people and their extraordinary interactions, you aren't supposed to think hard about the physics.

Procedural generation, on the other hand, is all about emergent behavior, which is closer to hard science fiction: tweak the rules and see what happens. You have to build some deep core physics that are robust, make all the other systems interact in sensible ways over a wide range of conditions, and not worry when balance goes completely off the rails in some cases (in fact, that's the fun part).

No man's sky is a space opera. You could imagine it being hard science fiction: digging into the ground could be deadly (as opposed to a reliable shelter), water / atmosphere mechanics could change (as opposed to just... water and air), gravity could have a much greater range, resource concentrations could vary more, etc. You'd need some mechanics updates to avoid making this frustrating, but maybe not so many as you need to keep the space-opera plot moving.