Another interesting way to split the difference: identify a need at $work that could really use a better open source solution that $work could use off-the-shelf

Another interesting way to split the difference: identify a need at $work that could really use a better open source solution that $work could use off-the-shelf. Go write that on your free nights/weekends as an independent open source project that's more-broadly useful to others outside of $work, and then when you're back on the clock, switch hats and make use of it. With this hybrid approach, you're still advancing the cause at $work, but you're not doing it directly or exclusively for them, and the open source project will have visibility, scope, and utility beyond $work and your employment there. You never know, it might even be the start of future promising career opportunities. There be dragons of course with how exempt employment and copyrights work in the US, though (as in, this might be a trivial case where if the side-project is successful, your employer can claim rights on it). You could come to some agreement with your employer ahead of time about the independence of such projects, though.