Hey there, first of all...welcome to TDH!
As for the Helmet...
The show used an entirely new sculpt with no lineage to the screen used OT helmets. It was a modified helmet that Legacy Effects made for their 1:1 Sideshow ROTJ bust. There are already casts made of it out there...at this rate I think they're going to become even more easier to get by the time Book of Boba comes out.