There has been no statement from aquacomputer, but I do believe all but the LT are EOL.
I did a quick google and the only 6 PRO I found was from a third party vendor from China on n
ewegg.com, at double the price, with a 33% positive rating. Not my cup of tea.
If an aquaero 5 pro will work.
performance pcs has a few of them.
What you may consider is an aquaero 6 LT with a
USB cable dongled to outside the case, and control with aquaerto on a laptop