Hardware wallets that you can assemble yourself:
Auditable and secure coprocessor (one to watch):
https://tropicsquare.com/product
User defined secure boot, ME neutralizing and desktop, tablet and mobile GNU/Linux hardware support:
Discussion
*Also, GNU/Linux server support, that's fairly well covered by many manufactureres though; the minis provided by these companies included. TV is another with that form factor, although not marketed often as such.