Good points Hear to Learn.
I lOVE Hook Theory.
But I can't fail to mention that Hook Theory is pretty big on:
I (C) ii (dm or dm7) iii (em or em7) IV (F) V (G) vi (am or am7) and VIIdim (Bdim) and I (C--back to root)---in the key of C as the example here---mean in every key, and how they relate to songwriting.
https://www.hooktheory.com/