It is very hard to get low resolution small oled screens. Cell phones use pentile displays that are about 60% the actual RGB resolution of the input they need. You would be looking at it needing to be outputting in the 4k range on a 1440p ish display to use off the shelf parts.

If you wqnted to have a 1080p RGB oled it would need to be about 11" and that is too big. It would also have burn in issues with any reasonable brightness.