Played Scum & Villainy (run by Stras Acimovic​) at New MexiCon, and we had a blast at the table. It’s not overwhelmingly STAR WARS, it creates strong play momentum, and it fits nicely between prep/zero prep and rules-dense/rules-sparse. I think it would fit the “not too deep” but “not frivolous” mental space you seem to find yourself in. As per the Torchbearer suggestion, run it for a session and see where you and your players land.

You might also just consider serial one-shots to shift gears from longer-term campaign-play duldrums.

Just some thoughts.