Borland Turbo C++ (and Pascal as well) had great help documentation. Every function was thoroughly explained and there was a lot of examples. I learned C just by reading Turbo C++ help docs. I miss that time.
nand2tetris is free on https://www.nand2tetris.org/course
The course is also available on Coursera where it also offers free option if you do evaluation yourself ("auditor" mode).
And your wish is granted: https://github.com/swsnr/mdcat
mdcat can render images in iTerm2, Kiitty or WezTerm
It has a few quirks but great piece of software nonetheless.
Microsoft PowerToys also contain a new neat launcher called "PowerToys Run" which is similar to Launchy. It supports various plugins including Calculator.
I like the feature that it shows up on the display where the mouse pointer is currently located so you don't have to jump between displays.