You’ve already had such good advice so much of this will be a repeat/ endorsement from me: I would go Peter nn Pip/Pippin. I love Pip and Pippin for a boy, and with your last name Pippin works especially well. And I really like that this means your husband gets a boy name mention.
I think Peter Ephraim O___ would be so smart and lovely and as has been said, you could still use Remy if Pip or another P or other nickname doesn’t stick. (Rocky for Peter is very inspired btw! If this boy is a bit of a bruiser, may need Rocky out from back pocket.)
Other middles, with Peter (though I like Ephraim):
Thaddeus (if OK that possibly also from Theodore)
Simeon
Cornelius (I love this combo, Peter Cornelius O)
Laszlo
Cassian
Ignatius
Magnus
Hope this helps and good luck!