As far as I can tell, Panbo is the name of a blog, not a manufacturer of load shedding controllers. But it's a generic enough name that it could be I missed them.
I did stumble onto
this one from Paneltronics that might do the job. At $584 I guess it's not too bad, but I've got quite a few other upgrades ahead of that on my list.
I also found a few commercial ones like
this from ABB, but I'm pretty sure I'm not going to like the price any better.