[aidos]

3Blue1Browns Essence of Linear Algebra is my go to

https://www.youtube.com/playlist?list=PLZHQObOWTQDPD3MizzM2x...

[Grimblewald]

I think this followed or accompanied by axler is the way to go

[isaacfung]

This, betterexplained, ritvikmath, SeeingTheory will give you a very solid math background(I think they are better than 90% of the intro math classes in colleges).