I built an on-demand remote browser and safe link opener[1], and I made it open source[2] but paid license and no one paid.
I know people are using it because of the binary, npm CLI downloads, and use of the demos, and I had some inbound interest but mainly people who seemed to want to not pay, or were just prospecting tools for future possible features.
I think an issue is that these products are mostly for enterprise and big orgs, who mostly want to buy from established brands or connected people. I tried posting on gum-road and using my linked in premium trial to message possible customers, as well as cold email, but I guess this "product" is not meant to be.
That's OK since I was only releasing it to fund me as a layer of a larger product I'm building.
[2]: https://github.com/cris691/OuterShell.git
I know this is supposed to be about generating revenue but some others posted without revenue so I thought it's OK to share :)
I would say that it's really difficult. For the first year, it made less than 1k/month, which was not sustainable, so I had to stick with my remote fulltime job at Toggl.com. Spend 4 hours per day at night and entire weekend days to implement the app. And now, after 2 years, I quit my job and dedicate myself to Proxyman. Aiming to ship iOS build and move to Window. It's still a long journey I guess.
[0] https://proxyman.io