I have a thing about unique names- probably comes from working with children and having heard every name before

My husband named our son, Espen which is popular-ish in Scandinavia but you don't hear it much here. I have full naming rights on this baby and I'm sorted for a girl's name as I still love the one I wanted last time but I'm feeling so lost on boys names.

For our son I loved:
Jasper
Felix
But they have both increased in popularity and I'm glad we didn't name him them anymore (though I still LOVE Felix so it's sad to let that one go).

Other names I like but I think they're too popular:
Griffin
Milo
Otis
Baxter
Phoenix

A couple of names I'm considering are:
Otto
Paxon (Paxton is getting popular in the states though)

The problem with very unique names is I've often never heard of them before so I'd love to hear some suggestions if anyone has them. Thanks! Oh, I also love names with an X or Z in them!