[hytcxnqu] small pawn endgames

KPK is the smallest pawn endgame in chess.  this position, from https://en.wikipedia.org/w/index.php?title=Promotion_(chess)&oldid=995304725#Rook_underpromotion

8/6P1/7k/8/6K1/8/8/8 w - - 0 1

requires underpromotion to rook to win.  how often can the defender force underpromotion?  how difficult is it for the attacker to avoid going down lines that require underpromotion?  in general, how much does the attacker need to know both the KQK and KRK endgames to win KPK?

according to https://en.wikipedia.org/w/index.php?title=Stalemate&oldid=997202209#Effect_on_endgame_theory the KPK endgame would change radically if stalemate were a win.

KPKP is the next smallest pawn endgame.  to win it, you need to recognize which KQKQ endgames are won (most are drawn).  unfortunately, that's sometimes not so easy (though it usually is):

8/8/8/8/8/8/8/qk1K2Q1 w - - 0 1

mate in 13.  (previously.)  it takes many moves before the defending (black) queen is captured, perhaps even longer if we used a DTC tablebase.

are there rook underpromotion situations from KPKP, perhaps going into the difficult KQKR endgame?  (probably not)  (perhaps there should be: create a chess variant.)