I have indeed tried googling this, and i've come upon conflicting answers as to whether this is 1. possible or 2. wise

At some point in the past I followed the general advice of don't reuse keys. This has resulted in....problems. Between multiple needs for a key and multiple computers the situation is unmanageable.

I'm planning to chop that down to a smaller set of keys with some reuse. and the intention is to import those keys into yubikeys so while they *are* on a piece of hardware elsewhere vs just yubi keys, they aren't just walking around with me unencrypted everywhere.

I'm also hoping to remove the need to have most things talk to my cell phone for 2fa by using a yubi key (I don't always have signal/access and it's become a constant thorn in my side)

But i'm seeing some conflicting information about whether yubikey supports my usecase to
1. import an existing private key that isn't generated on the yubikey

1. restrictions to encryption algorithms? ed25519 is what I tend to use, and I can change that, but, this seems like a strange restriction to only support RSA and some older algorithms?
   

Keys are not yet ordered if I'm barking up the wrong tree, but I'd intended to place an order for 2. a USBA and a USBC. (Subsequent question, in the event i lost a USBA key, and lets say the USBC key is the only remaining, can i use it through a USBA to USBC adapter or vice versa if the inverse happens?)