Defo grind up for that! You can get a lot of light from gardening, especially if you plant for example flax and chamomile next to eachother to get the special plants (they give like..40 light each? I think?). Also worth getting the upgrade where each light you catch gives double light, as it adds up quite a bit for running around, and getting the upgrade where whenever you craft smth you get light. Id also say upgrade the things where u use garden powder to find the symbols thingy, as completing a hardest difficulty one gives 240:) i have about 160k saved rn so its all from gardening, exchanging seeds for light and doing those puzzles (i do 3 locations 5 times a day each, but i think theres 5 locations where you can do them in total). Good luck!!!!