Today I learned, you can have a java(card) implanted into you if you wished to do that for some reason: https://dangerousthings.com/product/flexsecure/
Finally, a GPG/SSH Smartcard that I cannot lose (well, if I do, I have bigger issues)
@benjojo I have a co-worker who did (something like?) this! You can feel the little pill-shaped implant in their hand, it's super weird/cool.