This is a long overdue response: I do have an Xperia 5 iv port because rinigus drove a stock based Lineage port just as voidanix hinted.
I am currently in between daily driving this and quitting zenfone. And hoping JP2 would be a hit just like everyone else.
I will probably come back here in a dozen months to compare the shrinking bootloader unlockability market, so stay (not so) tuned 
and enjoy freedom 