It should be available and allowed to be traded through a broker, but only “accredited investors” can place orders to purchase
Accredited/expert status requires meeting several requirements
$1M net worth, $500K “investment account” or something like that
There will be a higher trade commission or fee on each trade
And no L2 published quotes (as far as I know)
So, anyone can sell, just a different process (broker assisted trade), and buyers must be accredited
And no L2
Trading in the dark and you don’t know if there’s any buyers
spec
PS If anyone knows different, please chime in