I just (4th week tomorrow) started a similar thing with my company.
I work 16 hours / week and am on a support rotation (albeit 3rd tier). I only cover unplanned work on weekends. I took a 60% pay cut but keep all my pre-existing benefits.
So far it has been wonderful for my mental health, although with social distancing and the pandy it certainly has been difficult to keep busy some days. I am passively looking for supplemental work as I don't make enough to deposit into my savings. I imagine as winter rolls in this will be a necessity to stay busy/sane.
In the meantime, though, I have picked up lots of cooking, baking, and work on some personal coding projects. I have also been focusing much more of my time on art, which is really awesome! It's too early to tell but this might end up a more permanent situation for me (if not at the current company then maybe at the next one?).
I think this has also made me more productive at my job. I have 16 hours this week - what NEEDS to get done? What is a nice to have? Constraints are wonderful for productivity.