Like this. (I don't do 1.15 skript so this may not work, but it should):
command /queueme [<text>]:
trigger:
if {queue::*} contains player:
remove player from {queue::*}
message "&aYou are no longer in the queue."
else:
add player to {queue::*}
message "&aYou are now in the queue."
command /chooseplayers [<text>]:
trigger:
if size of {queue::*} < 2:
message "&cNot enough players!"
else:
set {_p1} to {queue::1}
set {_p2} to {queue::2}
remove {_p1} from {queue::*}
remove {_p2} from {queue::*}
message "&aYou are chosen! &e(##1)" to {_p1}
message "&aYou are chosen! &e(##2)" to {_p2}