Memorizing openings is dubious at best, unless you're already a very strong player. Most chess coaches will actively discourage studying the opening until the you've become sufficiently good at the more impactful aspects of the game. Things like, awareness of the board, not hanging pieces, king safety, tactical pattern recognition, calculating 2-3 moves in advance with precision, attacking, defending, basic endgames, time management, basic strategy, and instincts. Memorization, without understanding, is mostly useless in Chess.

Ehh endgames can quickly go from easy, a beginner could do it, to insane theory that IMs struggle with. Mating with a Queen? Easy. Mating with a rook? Sure. Bishop knight? That’s pretty rough. Knight knight vs pawn? Even Hikaru struggles with that one in blitz.

Give Lichess a go (mobile or website). It's got unlimited puzzles and has helped me tremendously and doesn't get monotonous