I FOUND A WAY TO HACK THE GAME. You can have as much money as you want-all you need is a program that can open and edit a JSON Source File, like Visual Studio Code. Open the save file with your program. Use ctrl + f to find the last appearance of "money" in the file. Change the number to the right to whatever you want your money to be. Close out the tab you have the game open on (clicking the back button isn't enough) to clear the tab-saved data. This should make it open up the opening menu with a "Load Game" link at the bottom. Load your edited save file and boom! You can have as much money (or anything else) as you want.
Good find. If you want a nearly universal technique, snatch up a hex code viewer and get multiple save files with the fewest changes you can manage between them, with the variable you want to switch being one of those changes. (So, for example, in this game you might want to run the same day exactly the same way except for buying one watermelon in Save A and five in Save B.) Then compare differences in the save files, keeping an eye out for the specific numerical quantity you were targetting. (IE What your cash was when you saved in both instances.)
This works across a wide, wide array of save file types - jsons, homebrews, rawtext, *.sav, etc etc etc