Here is my product: https://matchkraft.com/. It is a marketing toolkit. I think you need to ask for feedback, asking why users don't want to pay for a premium subscription. So far, you are getting new users that is a good sign you are going to the right direction. Maybe, who is your ideal customer or maybe your product is ok but need more visibility (maybe paying ads). Try to get active users. I really want to... Source: 12 months ago

Calling a 3rd party API: There is a complete ecosystem providing "google-sheets-as-DB". I personally tested and recommend https://sheetson.com/ but there are a lot more with free tiers https://sheetsu.com/ https://sheety.co/. Source: about 2 years ago

Make your own or select a pre-designed one here! Source: 6 months ago

Free Online Graph Paper might have something close. Once you pick a type of sheet, you can change some of the parameters then download a PDF. Source: 11 months ago

You might be able to print something close to that here: https://incompetech.com/graphpaper/. Source: 12 months ago

But if you really want to bake the grid, then my method would be to get a grid e.g. From some template. You can generate any size at incompetech. Then you open the grid pdf in inkscape, drop your map, pull the grid above it, adjust colors, scaling, etc. Then export as PNG, later convert to any other format you want. Source: 12 months ago

I'll also add a free* map paper option... https://incompetech.com/graphpaper/ Can custom create any size/shape. I have 30x30 sheets I used to "test" the plotter at work (ancient inkjet so it needed to be run every so often anyway) and a fair stack of 11x17 sheets I can tape together in whatever configuration makes sense for the map. Source: about 1 year ago