There is an area that you might have missed that does allow you to easily farm for money. It is really close to the shopkeeper before the hydra, but it becomes temporarily unavailable once you kill the hydra. It reappears after you beat the star. It is kind of hidden, but is meant as a place to collect Tulu's skills if you missed them or as a way to quickly level or gain items to sell.
There was definitely a lot of things to notice and it did end up a bit harder because of the weird time limits (like I said elsewhere, if you speedrun the game and skip everything optional and ignore the story, you can potentially beat the game in maybe 15 minutes, but I also had the issue where if you took your time, it could take well over an hour, so I tweaked the game a bit. Unfortunately, that did also mean players had less reason to explore.
Originally, the plan was for the player to start off with Nara farming and setting up a way to use energy to farm, but having some trouble with the experiment because it was too inefficient for anyone other than Nol, then after a bit of farming, Tulu would show up and approach Nol. This would have made the player start with some crops already to sell. There were other things that were scrapped as well for the sake of the time limitation of 20~60 minutes.
While I still want the light potion to be used everywhere (it actually has another purpose), I do intend to make it a bit more obvious. Part of the problem was that I didn't want to use plugins or to use scripts in a manner like plugins. This will be fixed once I change to Unity/Godot so that even if the player doesn't use the light potion, there will be lights to guide the player towards their destination.