My particular project is designed to run in AWS and help reduce my users' bills. I spent a lot of time and effort to make it as easy to install as possible and to minimize friction, runtime costs and security risks for my users (it's entirely serverless based on Lambda and can be installed in minutes).
The side effects of these decisions are that it's so stable,secure and easy to use that pretty much nobody really needs any help with it, and that it is quite unlikely to break in the future by itself(although I see it break from time to time because AWS often changes some things that I depend on but I usually address these quickly as well), so getting a support plan doesn't make so much sense.
I mainly get these support plans sold to a handful of very enthusiastic users who would otherwise donate much smaller amounts.
I tried to bundle these with a guarantee that the supported code is thoroughly tested while the trunk is best effort, but that doesn't seem to work yet.
For example
https://play.google.com/store/apps/details?id=com.iiordanov....
and
https://play.google.com/store/apps/details?id=com.iiordanov....
are the same GPL licensed software either gratis or for $5. Just buying it via the store is straightforward instead of figuring out where the homepage is, finding a donate button, entering credit card details... .
Having more non-gratis but free software would be a good thing
Industry associations seem to help, like the Linux foundation, where company stakeholders come together to fund the development and get a say in its direction - eg, if the different cloud providers banded together to fork mongo and/or redis in this way (to the unfortunate and severe detriment of the founders)
Possibly purism is pioneering a hardware driven angle too?