I think that you can create a mobile game but it is more likely for someone to try out your game on PC.You should focus on the Windows OS and add compatability for mobile if you have enough time.Although if your game engine is specificly for mobile give it a try I am sure some people will try it out!
I strongly recommend having your primary goal be to make the game browser-based with itch, as then people dont have to go through the process of downloading and running your game, it's just there and ready to play
*However after exporting as browser-based it usually isn't too hard to port to the other platforms if you're using something like Unity
