This already works, although only if you've previously loaded that image preview with the normal file manager. This is a bug for GNOME to fix, most likely
As a matter of fact, GNOME-Screenshot is no longer a seperate utility. You can still install it if you wish (e.g sudo apt install gnome-screenshot) although the included Screenshot tool is completely integrated into gnome-shell.
What you're thinking of is the UNIX Philosophy, neither GNU/Linux or FOSS in of themselves.
That is a side-effect of the Terminal having a fixed size, not Advanced Tiling. Try floating the window and resizing it, you'll notice that it adjusts it's size only to the grid of characters.
Neither is included, at least not the GUI for GNOME-Extensions. Note that Zorin wouldn't work without extensions.
I would personally recommend Extension Manager from Flathub anyways