this is not true.. if the last bit says xaa then it means he mustve used a paid service to sim/carrier unlock the device which changes the last bit to xaa.
n976v is definitely a verizon n10+ 5g.. i know because i had one for a while and did exhaustive research on it..
also, gcf isnt verizon.. no one knows exactly what it is but its some sort of global configurarion.. it also shouldnt be used..
that being said, the n976v only has a few possible csc i think like 4.. vzw gcf and one or two others related to vzw..
it should work tho once unlocked on other carriers but dont expect carrier specific stuff to work.. he might just need to change apn settibns..
to add, i dont think xaa is a csc on n976v.. so that could be part of his problem if and of the sales code or csc code is xaa..
fyi the xxx/xxx/xxx are sales code network code and last set is carrier id.