I’ve been determined to finally beat Zelda II and determine that I would do it without save states and without a guide.
I know Zelda II is considered a black sheep somewhat but I really think in some ways it’s more fun than the original although I’d still pick Zelda 1 over II.
It seems I was wrong in that you can't lock an item in a dungeon by beating it. But you can lose keys to a dungeon turning it into a mountain with keys inside. So using a later dungeon's key to skip a key could softlock you.