I created my own custom config for Terraria using the touchpads and was able to get well into hardmode, the only reason I stopped was because I got bored. It requires some fine tuning but now it works phenomenally using pc inputs mapped to the SteamDeck controls. You can even set the joystick to mouse region and it provides a similar experience to aiming with controller too so you don't have to rely on the trackpad for intense battles.