It's another point to negotiate. At my last company, I listed a bunch of things as my prior inventions and got explicit approval that I could continue working

It's another point to negotiate. At my last company, I listed a bunch of things as my prior inventions and got explicit approval that I could continue working on them. Then I pushed to expand that to being able to work on any project that wasn't competitive to my current role/projects. I framed it as "this is one of the ways I learn new things and bring useful concepts into this role" and have had zero pushback. Your benefits don't have to begin and end at salary, vacation, stock, and wfh.