Even with missing features, this is a lot to get done in a month! It feels like there's a good amount of customization, and the menus are descriptive and functional. The music and sound effects fit the theme well!
Maybe it's more of a personal preference, but I can get a bit lost in sandbox management games without specific goals. A few custom characters in the crowd could be a good addition and getting them into the gym would be something aspirational to work towards. Perhaps there can also be missions to give the players something more specific to do in a day.
While the gameplay isn't quite my thing and I didn't explore it too deeply, I can appreciate the colossal effort that goes into making something this complicated in such a short time! Very nicely done!