What actual "hats" can Hrothgar and Viera wear?

[Atmaweapon510]

I know the YorHa visor/cap head pieces work with Hrothgar with clipping issues that aren't too noticeable at a distance. Since they come with adjustable blindfolds, I'm guessing these flew under the radar.

Anyone other hats that they can wear?

[Nihility]

mostly just circlets, decorations like the dried flowers/feathers, and facial things like eyepatches
can also wear things that replace your entire head like the animal suit heads
pretty sure the ribbon from the achievements vendor works too but it's kind of hideous with most hairstyles with a ton of clipping since they decided to make it a goofy hair band headband instead of just a ribbon decoration

[Vahlnir]

They can wear the Fending helmets from the Eden raids but...they look so small it is comical. Not really sure how they managed to squeeze their fat heads ( I mean this respectfully, I love Hrothgar!) into the helmets SE provided them with. Had to be extremely painful and no doubt required some pretty hardcore lubricant to make it happen.

[A_moth_called_rose]

We can also wear the ironworks visors, and anything that's considered a complete head model replacement like the scion traveler helm

[Yencat]

the scion traveler helm

Viera actually can't wear that one, but Hrothgar can.