I really like the welch labs series on imaginary numbers which covers the first part of what you talk about -- leveling up the notion of what a complex number i

I really like the welch labs series on imaginary numbers which covers the first part of what you talk about -- leveling up the notion of what a complex number is. Though his focus was more on solving simple equations with no real roots, but really detailing how/what is really going on. It is a great precursor to then thinking about quaternions https://www.youtube.com/watch?v=T647CGsuOVU&list=PLiaHhY2iBX9g6KIvZ_703G3KJXapKkNaF https://www.youtube.com/watch?v=T647CGsuOVU&list=PLiaHhY2iBX...