I’ve never tried but heard good things about using track pads to play RTS. My suggestion would once you get the game installed is to look through community controller configs and try some out then tweak them to your liking.

Depends on how picky you are, but halo wars was made for controller. You can only get the first one steam, but you should be able to get it dirt cheap. Not the best RTS by any means, but I was obsessed with halo and it’s older so your battery will last for while playing it.

I know RTS’es are more complex but I have no problem playing dota2 on ps5 controller. Steamdeck has more buttons AND more useful trackpads. Tweak steam input and you should be fine.

I love playing the old Warhammer Dawn of War games, set up a skirmish and Im happy to play for hours, works just fine with the trackpad as mouse and left joystick for panning the camera. Also been playing Starship troopers Terran Command, so far I am really enjoying this as a modern RTS, so much fun setting a line of troopers against a swarm.

Anyway yeah, RTS works great, especially with some of the community controller builds.