To be honest, the current multiplayer system feels a bit silly. Being forced to bind your progress to one specific player really limits the gameplay. You can clearly see other ship cores out there on the horizon, but they’re completely useless if you’re stuck in a tethered session.
I’d suggest allowing character data to be saved independently—after all, we already have character creation, right? Players should be able to bring their characters between their own solo worlds and other people's worlds. You could even add a toggle for world owners to decide if guests can bring in outside progress or if they must start fresh. This would solve the frustration of not being able to play just because the host is offline.
In the long run, for this to feel like a "complete" game, every player needs to be able to explore independently.