The Alby Hub needs to be running on the public network for that.
If it's on the Alby Cloud or on a Pi at home this will not work.
But you find the node pubkey on the "Node" page -> "advanced"
Discussion
it might be possible also to use a cheap VPS with firewall forwarding to a wireguard connection to your home machine
but the caveat is that downtime is more likely, since if your house internet fails, or the pc running it fails, or the power goes out, these are things that data centers usually have strong measures against
having said that, i personally want to have two independent internet connections, a primary and secondary (probably cable and starlink) and a big chunky UPS for all my tech gear and to be able to do this home-server running
if the purpose of your hub is mainly to send out payments and receive them when you are at home and know it's online then it's fine... so long as your downtime doesn't trigger a force close by your channel peers