Thank you, God!
New commands 'split-root-window-below' and 'split-root-window-right'.
These commands split the root window in two, and are bound to 'C-x w 2'
and 'C-x w 3', respectively. A number of other useful window-related
commands are now available with key sequences that start with the
'C-x w' prefix.
From the latest #Emacs news file.
https://www.gnu.org/software/emacs/news/NEWS.29.1
via #MickeyPetersen’s post
https://www.masteringemacs.org/article/whats-new-in-emacs-29-1
Original: https://toots.dgplug.org/@jason/110812336560734206