I don't think 1080p at a 7 inch screen is a good idea, 720p should be enough is enough in pixel density term. You're gonna need bigger than 7 inches.
As for the biggest technical issue would be the battery life, 1080p consumes more power and it needs something better than OLED, well optimized CPU power efficiency and well crafted internal battery pack.
I'm begging you. Before you give your Switch Pro takes. Please look at the pixel density of 720p at 7 inches. It's 209 pixels per inch, which is equivalent to a Retina display if you hold it 16 inches away from your face, which you almost certainly do if you are an adult. pic.twitter.com/Cy2fV3663o— Jeff Grubb (@JeffGrubb) March 4, 2021