Hi, please not that if the displays locks onto a certain frequency for example 60fps because you are gaming you cannot have a part of the display running at a higher refresh rate for example 90 without adjusting the whole refresh rate of the panel which can result in longer frametimes on the game.
Also keep in mind that under low light conditions the vrr is disabled and the panel locks on 120hz
you will be wasting processing power and also may screw up the frametimes in the game momentarely, that is probably why they have not done it like that
they are not locking the refresh rate because battery life and heat generation are out of the window.
Also the s20 did not have an ltpo display hence why they where locked at 60hz or 120hz.
As I said if you are running a display at 60hz duing a game and receive a notification and the screen runs at 120hz while the game runs at 60hz and that happens out of nothing the frametimes can be momentarely screwed up in the game causing tearing or stutters. I do not think that a 60 hz animation of a notification would make a big difference, if you say it is sluggish then probably the phone is not being able to push 60 fps in that game or moment and therefore the screen scales down in rf to sinchronize with the fps pushed by the gpu hence why you say it is sluggish
Well no one cares about what apple will do when it will come out in 2030 on iphones.
Just look over XDA developers forum, I am sure someone has written a few lines of code to set 120hz static.