Any such discussion - like those of "the best" suffers from lack of definitions and therefore of metrics. What does one mean by "the worst"?
It doesn't need any definitions.
When a group of people who play chess, say a chess tournament, finish the competition there is usually someone who is in last place. That person (or persons if there is a tie) is considered "the worst" within that group.
So "the best" is going to be a country that has players who have high ratings, do well in tournaments, etc. Countries that might be considered "the worst" would probably be ones with low rated players (or possibly no rated players), players who finish poorly in tournaments, etc.
The only exception I can think of is a small, isolated country with a substantial prison population. Prison inmates always seem to be good at chess.
One always needs definitions - you've presented a number of different metrics there, and different countries could potentially be last according to which ones you use. British Virgin Islands finished "last" in most recent Chess Olympiad, but at least they sent representatives so maybe it's fairer to say they finished 188th, and the other countries who didn't send anyone are "worse" https://www.chess.com/events/2024-fide-chess-olympiad-open/results
What if there was a player from one of those countries higher rated than anyone in the British Virgin Islands but just couldn't go last time? That was mentioned earlier.
Flip it to the opposite: what country is "best" at chess? That is impossible to answer without choosing one or more ways to measure it ie. to define what you mean.
Any such discussion - like those of "the best" suffers from lack of definitions and therefore of metrics. What does one mean by "the worst"?
It doesn't need any definitions.
When a group of people who play chess, say a chess tournament, finish the competition there is usually someone who is in last place. That person (or persons if there is a tie) is considered "the worst" within that group.
So "the best" is going to be a country that has players who have high ratings, do well in tournaments, etc. Countries that might be considered "the worst" would probably be ones with low rated players (or possibly no rated players), players who finish poorly in tournaments, etc.
The only exception I can think of is a small, isolated country with a substantial prison population. Prison inmates always seem to be good at chess.