What about interaction with #2, #3, #10, #27, #31?
I assume that I move to these locations when all other players are on #20.
#2: Exchange 1 banana for 2 fruits (I have a banana)
#3: Draw 1 fruit, then exchange 3 fruits (other players have 3 or more fruits)
#10: Receive 2 fruits from the richest (I'm not the richest)
#27: Collect donations from the rich (I'm not the richest)
#31: Exchange all fruits with another player (other players don't have 2 or more fruits in their hands than me)
Can I fulfill the necessary requirements of these locations or not?
I think that in all of those situations, it is impossible to follow the instructions on the card, so you would get the signpost draw action instead. There shouldn't be a meaningful difference between the richest player being protected by #20 and the richest player being you. In either case you aren't able to take cards from the richest player.