I would like to play this game. I did realize that 21 corn on the ground is too much at once (two trips to the water per day is only just barely possible). If I can make a suggestion in that regard, walking one step could maybe be 1/3 or 1/4 of a time step, so that filling the can, hoeing the ground, and harvesting can still have the same time cost, but walking across the yard or exploring would be a lot less time consuming. 1/5 would be exactly one minute, so that’s another possibility, though it might be difficult to balance the movement of enemies and combat actions with any time system like this.
The sky is truly the limit, so I hope you continue! Tool upgrades and tree seeds would be easy concepts to steal, but don’t be afraid to break with the Stardew / Harvest Moon elements. No idea what worldbuilding you wanted to get to, if any, but I half expected monsters to attack the farm at night. Something zany like chaining up a zombie to a post and running in a circle around him to make him plow the ground would be a good use of the roguelike staple of “systems interacting weirdly”.