If you just want that you don't need spacemacs, just evil mode.
Well, I physically cannot take the keystroke geometry if stock emacs for any stretch of time; the space bar approach is crucial for me.
Evil mode supports leader keys. It’s pretty trivial to setup.
The real value of Spacemacs is which-key and having everything already configured with semantic leader key setups. Like you can absolutely do that yourself but at that point you're implementing Spacemacs.