List it for free on a local facebook audio enthusiasts group. Some young lad/lass who’s broke as a joke, but, loves music will pick it up and should (hopefully) have some fun with it.
If you put it on facebook marketplace, some regular utilitarian creature with no interest in music will pick it up and immediately resell/try to make a buck off of it.
On second thought... and sorry to be blunt, but, those speakers look like they are poorly designed (to begin with) and probably sound bad, i.e., a poor design coupled with 40 years of degradation. So, maybe, FB marketplace is fine for this speaker too.
If i were donating stuff that’s competent and sounds good (worthwhile), i will list it for free on the enthusiast groups and hope it reaches someone capable of enjoying it.