Question

I'm an indy dev and I just made an online, multi-user notepad style calculator

Answer 1

As someone that uses Google sheets for hobby game design I might be a bit biased but what benefit does this have over using Google sheets? Personally I think the most valuable thing you have is your templates but that's something you could do in sheets as well. Regardless, kudos on completing your project, that's an achievement on its own. Just because something exists doesn't mean you can't make your own version that's more to your liking.