It would be nice it be able to keep the HUD portions of the Pneumatic Helmet (leaving the protection behind) as a head slot curio.
Thematically, maybe extract out just the eyepiece and electronics.

Upgrades such as the block or entity trackers would work, but item life, armor, and maybe scuba would be restricted to only the real helmet.

This is a nice idea, but not something I'm in a position to implement right now due to time constraints. But I'll keep it open.