If this is just meant to be a random prototype, I would just move on to the next thing. If you're trying to turn this into something to make money from, here is my feedback.
The pixel art style and default UI elements are both off putting as well as very low effort. There are several free / cheap assets on itch that you could have used instead of programmer art, and I would recommend doing so if you do not have the means to hire someone directly. The issues I have with the visuals alone makes it rather difficult for me to be invested in your demo; not just because it clashes, but also because it feels like you didn't put too much effort into it. First impressions matter.
In regards to the audio, the music is not bad. I don't have too much feedback to give here. Maybe change the combat music to fit the situation. e.g. more doom/gloom if you are in a dire situation ( actively losing ) and/or a more hyped track if you are currently winning the fight.
As for the overall concept: Unless I'm missing something, the gameplay loop is supposed to be a more simple version of Gladiator Simulator: Arena War, but in a hex-based grid? If so, I would clean up the menus a bit, improve on the art style and audio, as well as look into QoL features such as dismemberment being visually represented as well as impacted in-game. One of my characters took out an enemy's leg and it didn't really do anything to him. You'd think it would be considered a dismemberment and he would be out of combat or bleed to death relatively quickly.
Another idea to consider: right now you only obtain money from winning fights. Being able to capture enemies by knocking them out ( % chance increased from blunt weapons / Stun ability ) to have them fight for you or be sold off for money would be nice. Alternatively, having randomly generated bonus objectives could help as well. e.g. Win within X seconds, win without any of your units losing Y% blood.