Forgot to post here as well, I made a second demo with a trick implemented to make the border artifacts unnoticeable.
I simply render extra pixels outside of the screen, 25% to each direction.
And to make sure there not too much overhead from rendering extra pixels, I used variable rate shading to render the pixels beyond screen at a 4x4 shading rate which is like only 1/16 pixel count.
P.S.If you find some artifacts like pixelating shadow/sun/glare it's because I didn't have the time to distinguish which pass should have variable rate shading applied and which pass shouldn't, so I just apply to all of them, it doesn't represent what it should look like in a normal game.
And you need to turn on resizable bar to run this demo since I used GPU Upload Heap.
Download: https://drive.google.com/file/d/14pFabiYpCwH10DLxjmYiBhyQ339wi3WU/view?usp=sharing