Dump unsaved diff from the current buffer into new buffer (with diff language pre-selected)

[mandx]

Sublime Text has this feature where it can show in a panel a diff of the buffer's content and what's on disk:

I wonder how can this be replicated with Helix?

Ideally, I would just run something in the command bar, I was thinking of:

:sh cat $contents_the_buffer_somehow | diff $filename_of_the_buffer - | piped_to_current_hx_instance_but_in_a_new_buffer_somehow

(note the - as the second argument to diff)

And we would get something like this:

And it would be just a regular scratch buffer, it would simple come pre-populated with the diff's output and it would have the language set to diff, but otherwise nothing out of the ordinary.

Is this possible right now? Or would a plugin be necessary for this?