Wanted to add a request to add other yubikey feature sets if at all possible (I’d really like to replace my yubikeys completely). I use a yubikey for various smartcard/ssh login workflows and email encrypt/decrypt. Found this infographic of what yubikeys currently support which was helpful. Not sure if any of this could be added through ‘apps’ in the future or not
We are on it 
Thanks Zach! Looking forward to my Prime shipping soon to test