I was hesitant to add my own but I think you might find it interesting as we make money not from clients but from grants.
We have IronCalc[1]. We don't make money from customers as we don't have a finalized product yet. But we have an ongoing grant from the NLnet[2]. You can have a look at the kind of projects they are granting money. It's always a source of inspiration.
That being said IronCalc takes a lot of time from me. Way more than a side project should.
This is lovely! I'm surprised I had never heard of it before today
The friction to try it out is already really low, I like that! But it could be even lower if instead of an image the interactive version is served right on the landing page. Great project!