there is a failed kickstarter from five years ago[1] which imagined an alternative to the traditional spreadsheet software. I imagine it would be fun to work on building such a thing, and I already know it would be more usable than Excel etc for many situations.

e.g. the company I work for give me a credit card to use to buy fuel for my car, with a soft limit (i.e. nothing technical to stop me spending more, but they may revoke this privilege if I abuse it), and there is an additional discount which is not displayed at the pump or on the receipt. I track how many litres I purchase, along with the pump price at the time, and currently use Excel for this. But it's not really designed to show me how many litres I can still spend before the end of the month, based on recent fuel prices etc. I believe such a solution could help with this, but the dev that had this idea only wrote a UWP app, nothing cross platform or super fleshed out...

[1]: https://www.kickstarter.com/projects/395431036/threads-a-mod...