Demap is an Emacs package that adds a minimap buffer that shows a zoomed out view of the active window. It updates what it is showing has you change the active window and it can be detached, moved, hidden or killed like any other Emacs buffer.

That last screenshot has Solaire-mode, Doom Emacs, the theme doom-one, and the font Minimap. The configuration used for it is:

(setq doom-theme 'doom-one)
(after! (solaire-mode demap)
  (setq demap-minimap-window-width 15)
  (let ((gray1 "#1A1C22")
        (gray2 "#21242b")
        (gray3 "#282c34")
        (gray4 "#2b3038") )
    (face-spec-set 'demap-minimap-font-face
                   `((t :background ,gray2
                        :inherit    unspecified
                        :family     "minimap"
                        :height     10          )))
    (face-spec-set 'demap-visible-region-face
                   `((t :background ,gray4
                        :inherit    unspecified )))
    (face-spec-set 'demap-visible-region-inactive-face
                   `((t :background ,gray3
                        :inherit    unspecified )))
    (face-spec-set 'demap-current-line-face
                   `((t :background ,gray1
                        :inherit    unspecified )))
    (face-spec-set 'demap-current-line-inactive-face
                   `((t :background ,gray1
                        :inherit    unspecified )))))

You can do M-x demap-toggle to open and close the default minimap to the side of the active frame. If you just want to make a standalone minimap buffer, do M-x demap-minimap-construct.

The side and width of the window that demap-toggle opens to show the minimap can be changed by setting the variables demap-minimap-window-side or demap-minimap-window-width.

(setq demap-minimap-window-side  'left)
(setq demap-minimap-window-width 15)

You can change what windows a minimap can show by setting the function in demap-track-window-mode-update-p-func. For example, you can make minimaps only show windows in the same frame has it by using:

(defun my-track-window-update-p()
  "my minimap update predicate function."
  (and (demap-track-w-mode-update-p-func-default)
       (get-buffer-window) ))

(setq demap-track-window-mode-update-p-func #'my-track-window-update-p)

when the window the minimap is showing is not the active window, the current line and visible region overlays change face's from demap-current-line-face and demap-visible-region-face to demap-current-line-inactive-face and demap-visible-region-inactive-face respectively. By default these new faces are the same as the usual ones, but these faces can be changed to have a visual indication of whether you are in the window the minimap is showing or not.