Unpaid Visiting researcher?

I have a PhD and am a postdoc fellow at my university. I’ve lived abroad at one point and have traveled a lot, so I was thinking a cool thing to do would be to visit a lab in another country who studies something similar but uses a technique that I want to learn. My PI is on board with this. Essentially, I would be ”wfh” for my current postdoc job and would be visiting this other lab that would not need to pay me.

The idea is that I could visit for 1 month and maybe also present a seminar on our research.

Is this something that is done often or generally allowed at universities? Any advice?