I can see the slight similarities with Steadfast/British Bulldog. I think they look a lot like Under Two Flags in GBE style. UTF is gone now but if you go on the gbe website, you can see what I'm talking about.
How sure are we that these little fellas are French? Seems to me that Sun
helmets went out in the big WW1 and I doubt the french were up against armor in Viet in the early 1900's. I might even say that the set is British.
Mysterie continues... Mike