Stealth should be useable on planets
Arguably why not really? If you cloak a planet (if it has pops) it should reduce other empire’s intel on you, at the cost of a lot of monthly energy cause why not. The means to counter it would be to use espionage and science ships to discover hidden sections of an empire.
Can make you seem weaker than you are before war, make for interesting strategies as you bide your time before showing your hand.
Long term, you can enact planetary decisions on it that other empires might not like, like a prison planet that has a test subjects planetary decisions that was outlawed by the galactic community, or testing weapons on a barren planet that was also banned by the galactic community but face no drop in opinion until discovered.
Why not have something like this?