Scotland need to win and they’ll qualify. Nothing less will do.
Wales need to win to be certain of qualifying. If they draw, they need Ukraine v Croatia to be the same or lower scoring draw than their own draw.
Ireland (need a miracle) must win, probably by 3 or 4 goals, or, if less, need N Ireland to get beat by 2 or 3 goals OR Ukraine v Croatia to be a draw.
N Ireland mustn’t lose by more than one goal to be sure, or they rely on either Scotland losing, Ukraine v Croatia being a draw, or Wales v Ireland being a draw or Ireland not hammering Wales.
Then nobody needs to draw Italy or Portugal or even France if they fuck up their last game.
HTH.