Most macbooks I remember since a long time ago were pretty much instant on way before apple sillicon. Maybe you had some corporate crapware installed in yours/.

Depends on your definition of "instant".

What we really mean is before you complete the action of fully opening the hinge to 120deg which is something like 1.5-2seconds?

AFAIK pre M1 days it would be still a few seconds after fully opening and now it's more like < 1sec.