I may be a broken record, but that’s a JJ Abrams lack of vision. Disney just let him do whatever he wanted.

Alternatively, you could find a way to make Starkiller Base something else, maybe even combine it with Exegol? Or just take away the planet destroying nonsense.

You could treat this as a 3-in-1 epilogue film, taking the pieces you liked from all three and morphing them together while still using TFA as the backbone. You’re already blending 7-8, maybe bring some of those other scenes from TLJ up to create a new second act instead of the destruction of the Republic. Make it more about stopping the First Order before they can take control rather than fighting them after the fact.