Drop-in 6mm or 22 Grendel barrel for Howa mini - anyone do them?

[Bat Rastard]

Preferred told me the are open to Group buys. The price depends on the number barrels bought. https://preferredbarrelblanks.com/pre-fit-gun-barrels/ They have both the 6mmAR and the6mm Trubo40 chambers. They also have the 22AR.

I would likely be a participant in a group buy.
Do they all have to be the same thing?
I want a 6 or 22 Grendel for a Ruger Predator.