Saint Pierre and Miquelon is less than 20 km from the coast of Newfoundland (Canada). It shouldn't be that hard to get stuff delivered there.
There's a ferry that runs between St. Pierre and Newfoundland a bunch of times every day. It's still running. Regular flights to St. John's, Newfoundland, even Paris, France are still happening.
I don't understand this at all -- it's not like USPS was literally flying a plane to St. Pierre, was it?
Samoa even more so, given they had a high death toll from a measles epidemic there two years before covid struck.
In recent times, it was the source of tax-free, cheap Canadian cigarettes and Canadian booze. Neither of which the local French population consume, but are more than happy to sell it to Newfoundlanders visiting :-)
if the price is worth it, USPS pays. if the price isn't worth it, then USPS stops delivering there.