Congratulations on baby 4 - your kids have charming names!
for what it’s worth, it doesn’t feel too out of place with the likes of Hezekiah, Ezekiel, Emmanuel, Abraham, Messiah, Eliam, Jeremiah, Jasiel, Ozias and so on which have been in the charts.
I do think you could use it, since it is Biblical - so long as you don’t mind the associations - plus nickname Remy adds a slightly different spin to it?
Peter feels like a solid, versatile choice - and one you’ve loved for a long time. Do you think you’d regret not using it?
You could to Peter Ephraim ‘Remy’? maybe? from Peter Ephraim?
Other nicknames could be Pip, Rocky, Pez (PEHZ), Pal, Patch…plus any others that come about naturally?