4/ Given these considerable hurdles, unless the FDA changes course (unlikely IMO), will vendors of such devices find non-US revenue streams to stay afloat?

So-called "anti-choking" plunger devices were introduced only about ten years ago. Will they still be around a decade from now?

We shall see!

3/ To my knowledge, no devices of this type have met Class III requirements, an expensive, complicated, time-consuming process intended to protect the public from products of unproven benefit & safety.

2/ What happened?

According to Amazon (and other sources), the FDA now requires that, in order to be marketed legally, such devices must be registered as Class III, the agency's highest, most demanding classification.
sellercentral.amazon.com/help/hub/ref...

I have tasted
the sandwich
that was lobbed
at my bulletproof vest

and which
you probably spent
your hard-earned
money on

forgive me
it smelled delicious
so onion-y
so mustard-y

"I could smell the onions and mustard."

Actually I would be an ass and ask to see about ballistic vest and ask to try it on and have the other jurors throw sandwiches at me.