Not as a second job, not as a side project, and certainly not as a charity case that just flat out will not sustain you.
There are precious few things that have the adoption and support linux has, and a lot of that is very much a "right place, right time" thing. The fact that I've seen plenty straight up vilify a coder for daring to want to, you know, make enough to support a library full time has always struck me as self destructive. I'm sure many great coders have given up and moved on to paid projects doing boiler plate because inventing new stuff gets you chewed up and spit out by the community if you monetize.