This is not really an answer. Just a too long comment to post in as a comment.
I have quickly had another look now. I think you could just (globally or in your preferred evil-states) rebind the
previous-buffer functions to your preferred keys. You can use e.g.
C-.. Although they are bound to flyspell and evil function by default, I never use those. So you can unbind them and bind the buffer switch function by adding the following lines to the
user-config section of you .spacemacs file:
(define-key flyspell-mode-map (kbd "C-,") nil)
(define-key flyspell-mode-map (kbd "C-.") nil)
(define-key evil-normal-state-map (kbd "C-.") nil)
(define-key global-map (kbd "C-,") 'previous-buffer)
(define-key global-map (kbd "C-.") 'next-buffer)
Then optionally you could activate also
Personally I think
SPC b n is inferior to using e.g.
C-tab like in most standard applications. Emacs 27 provides tab-bar-mode so that you can use
C-tab for switching between window configurations. Also there is a tab-line-mode which lets you switch between buffers. I think you should play with these modes and rebind
next-buffer functions (e.g to
C-. which correspond to the
> keys without pressing shift). There is an unfinished centaur-tabs layer that you can try and install and from which you might get some inspiration. I stopped working on the layer as I thought I should start from the basic
tab-line-mode functions. Also I think even the tabs are unnecessary, we could just cycle over buffers while showing them in the minibuffer (instead of listing the buffers in tabs). But a package still has to be developed for that (I think).