K+p vs K chapter is absolutely crucial, you should be able to win/draw those against stockfish with your eyes closed. "Piece vs Pawn" chapters are highly useful too. B+p vs B (same coloured) is pretty straightforward and shows some handy technique so you might as well get that too.
"B vs N with one pawn" is obscure and requires more calculation than actual knowledge. B+2p vs opp. B is tricky, but not TOO tricky. Try grabbing it if and if it goes well, go on.
"Multiple pawn" endgames HEAVILY rely on calculation, but are extremely beneficial if you master even the basic ones. I'd say, for now go for K+2p vs K and p vs p, as they will arise often in your actual games.
As for rook endings, go for the basics (Lucena, Philidor, last rank defense) because everybody should know them.
My two cents on that.
I bought 100 Endgames You need to Know (on Chessable). Things are a little complicated for me beyond the first six chapters and I was thinking I could maybe leave them out until I reach a rating of 1200 (my end of year goal)? Any thoughts on this?
If anyone has this book I was also wandering how long it took you to learn the endings? I have had the book for just over a month and I would say I am about half way there with the first six chapters. I switch back and fourth between re-reading the chapters, watching youtube videos on the endings and reviewing the moves daily.