I used Nim for my implementation of Make A Lisp[1]. I use Python every day and the jump was pretty straightforward. Almost copy and paste from some things. I don't have to think about static types much, but it was a welcome change. I loved having macros to play with, too. I spent a lot of time with docs which aren't bad.

As for the "mental capacity" I felt the same about finally getting into Rust. Spending some time with Nim actually helped me bridge the gap from Python to Rust.

[1] https://github.com/kanaka/mal