Linux

Not even Basic Command-Count-motion like c3w aka change 3 words after cursor, or d3b delete 3 words before the cursor?

To that, you add the D aka delete command C for change Y for yank (copy)

So yy to yank line, or dd to delete line.

Also p for paste

Also, i sends you before the cursor, a sends you after. Capital I is insert at beginning of line, Capital A is insert at end of line (append).

I terms of motions and moving around, you need: hjkl, C-d and C-u (half page jumps down and up), and within the line: 0 or ^ for beginning of line, $ for end (taken from regex), w for moving by word forwards, b for moving by word backwards. That's pretty much all you need imo. There is also t and f. Where t goes forwards (think 'till aka until). Like dtc delete until the c character. F is the same but goes backwards in the line rather than forwards. Remember you can use these with xommands, so d$ deletes until the end of the line. Or "dt." deletes till the "." so.... yeahI know there's more, but that's all you need for Normal and Insert mode imo.

For Visual mode, you only need to know how the Visual modes work. Visual (v), Visual Line (Shift-v) and Visual Block (Ctrl-V).

Also, for visual mode, it might be helpful to learn how to use V-Block to comment out multiple lines at once. Can't be bothered to go into it.

But I'd argue that's all there is to learn about vim keys in terms of getting work done.