Can't Add SSH Key to GitHub CLI

Ubuntu 20.04 LTS

Following this guide

I created a keypair and added to the ssh agent following another guide. I gave it a password

After generating my keypair, I added it to the ssh agent with

ssh-add [path-to-private-key]

Finally, I try to add to github cli using

gh ssh-key add [path-to-public-key]

and get an error

open [path-to-public-key]: permission denied

public key file permissions:

-rw-r--r-- 1 [username] [username]

.ssh directory permissions:

drwx------  2 [username] [username]

Any insight is greatly appreciated