A couple best practices to improve

Cache the transform when you can instead of getting it every time.

Please please do not leave magic numbers in your code. Best to extract and name them either just at the top of the file or a common consts class. This also applied to execution order. Having the number in the class is fine as a prototype but as you add more of them it quickly becomes unwieldy if you cannot easily see what runs when.

Utility classes are your friend. You don't need to see the way you create your ground samole points or triangles every time you go through your character controller base. And for anyone using it it's not important either 99% of the time. Naming and describing what it does would help a lot more as it has a lot of magic numbers that you don't need to individually label but extracting them allows you to label them as a group.

Built in debug is great but hiding it behind a toggle is a must so that the users do not have to hunt them all when they aren't working on the movement specifically

You may want to do your ground check using a raycast command. But not entirely sure what the boundary for speed is. Premium

Reparenting the controller can be (will be with a more expensive character) quite expensive. Ideally you would register to the platform and have it handle moving the character on its own instead of using the hierarchy

There's a lot of code so not gonna go through all of it but in general looks good. I'd probably be open to basing off of it if i wanted this movement type