After going back and forth on whether I wanted a Yubikey, I finally decided I didn't want to support them due to the closed sourceness.

I bought an Open PGP Card instead! https://www.g10code.com/p-card.html

You still have to buy your own card reader, and any card readers on the market aren't as small as the Yubikey... but it's a fantastic device and I love mine to death.

Note: the yubikey actually uses the open pgp card inside of it (which the actual implementation from the chip supplier is hardware-closed-source, although the reference architecture is open). The nitrokey too. They technically all have closed source with the BasicCard that runs inside them! With that in mind the secret-sauce of the yubikey is also closed source, where there's no secret sauce around your OpenPGP Card to be closed source.