CANNED AIR

[Tarmunora]

I mean, there are oxy-dep medkits around, which contain salbutamol (standard med-grade chem, though a total PITA to make) pills, which heals a hefty 6 oxy and 4 losebreath per life cycle, more than enough to spacewalk without internals I believe, and as Wisecrack said, basically fill the role you want. There's also perfluoro, which is... way easier to make(?!?) and restores 25 oxy damage per cycle and locks losebreath to 6 (All chem details taken off of the wiki)