I played this on my laptop so some of my feedback and experience with the game isn't with its intended platform, but hopefully this feedback will be of some help.

Some stuff I'm pretty sure you already know:

• AI doesn't fight back, but I'm fairly certain that this update was planned to work on the movement and fighting combos, so I didn't really dock any points for this in case you're wondering.
• No music in fight. Some basic Kevin Macleod fight music would make the game more entertaining and get the player pumped in my opinion, but since you had several issues encountered with trying to get this version out I'm not surprised that music wasn't included.
• The movement is a bit awkward on mouse and keyboard, having to drag to move makes movement feel more sluggish. It wasn't too much of a hindrance this time, since I was mostly moving only to get closer to the AI after they were knocked down, but in an actual fight it could be really cumbersome. But again, like you said you're aiming for mobile release not PC, so I can't say for certain how it will work then.
• There is no settings menu.
• Nothing seemed to happen at the end of the countdown timer.
  

Feedback I think will apply just generally:

• When the AI is knocked down, its impossible to hit them from any angle except at the legs. I think it makes perfect sense that you can only hit the NPC by kicking if they're knocked down, but perhaps the colliders should be adjusted so the downed enemy can be hit from any direction.
• On the topic of knockdown, the NPC never seemed to get back up unless I attacked them. I imagine there's plans to make the NPC able to jump up after a few seconds if the player doesn't attack them while down, and since they can't fight back there isn't much benefit to it at the moment. But definitely should be kept in mind for future updates.
• The devlog mentioned a win animation, I didn't see any for the MMA stance or the Capoera stance (or however its spelled).
• Sounds for the hit impacts are fitting, but perhaps some variation on the visual effects would provide some nice flair in later updates. Maybe keep the current red impact effect for punches and maybe have yellow for kicks, and special combos like the uppercut that can knock enemies down can have like a blue coloured effect. Depends on how exaggerated you wanna get with the game.
• I love the Mortal Kombat style knockdown, that should definitely stay in.
• The animations look nice.
• The ability to change stance is kinda neat, and I like the idea of being able to customize fighters even if not much is implemented yet.
• UI is easy to understand in the combat scene.

Overall, a decent start for a mobile 1v1 fighting game, nice work!