Are outdoor receptacles required to be GFCI receptacles in the US?
Any GFCI protection will do

When the code says something "shall have ground fault circuit interrupter protection for personnel", it does not care where that GFCI protection is provided -- at the outlet via a receptacle-type GFCI, upstream of the outlet using a receptacle or deadfront GFCI device, or via a GFCI branch or feeder breaker.