Khan Academy courses are intended to supplement a complete course in the subject, which would presumably have exercises.  Does whatever linear algebra class you are taking not have exercises in its textbook?

They do, but there's not that many of them and they are all of uniform difficulty. I need problems that help me practice my foundational understanding instead of the problems I get in the course, which all assume that I developed strong foundational understanding off the text. For example, if I go to the multivariable calculus course in KhanAcademy I can get exercises on basic partial derivatives, which I can use to gauge how much of the reading for my course I understood, before I move on to my course's textbook problems, which are of a much higher difficulty.

It will take an extremely long time to create exercises if it is ever done. I think at some point you need to go outside of Khan Academy.

I can understand your course textbook being hard to read, but why don't you use math stack exchange and ask a question if you get stuck. You could also use matrixcalc.com or emath.com to obtain solutions for a given problem.

A reason you may be finding linear algebra hard is not meeting the prior knowledge e.g. discrete maths.