I'm currently attempting to setup my personal GPG key suite for the next few years, and I'm running into a question I don't have a ready answer for. I own 3 yubikeys, Primary/Secondary/Offsite Backup. I'd like to put a different GPG key on each so I can revoke a single key at a time in the event of a key loss. The plan is backup those private keys on usb drives off site as well. All pretty straight forward. (these keys are used as ssh keys for servers, github, commit signing, and the odd file encryption).
I'd like to know if I can use the GPG "web of trust" to sign one "master master" key and assign transitive trust to all of my yubikeys at once. As I understand it, this should be possible, but I don't think this property will apply to any SSH keys I export, nor do I understand if/how github would mark the sub gpg keys used for signing.