Interesting take on Into the Breach, with no buildings but a lot more units.
The attack descriptions should show exactly how much damage each attack does. Also the currently selected unit should be highlighted. Other than that the UI seems to convey all the needed information.
3 actions seems a bit low with the number of attacks you have to deal with at once, though for the demo it was barely enough to scrape by. Also I wish your units had more mobility as the battlefield ended up getting pretty cramped. Having flying units or units with more movement would help a lot.