I used to be a rope access worker, mostly for consstruction, maintenance and inspections in hard to access places. Most knots are only useful in very niche situations or to impress your friends. You probably don't need more than 5 to solve almost every situation you could realistically get yourself into (eg. Figure height, alpine butterfly). In a lot of cases, the fancy knots you see online are only usefull because they are easier to untie after getting loaded (eg. Using figure-nine instead of figure-height) and you can ignore them.

I would recommend looking at the ones that are thought in the Irata and Sprat certifications. IIRC there is fewer than 10 but there is a wide range of ways you can use them or combine them together.