Hello @HoneyScammer,
I used the 5.6 inch AT056TN53 V.1 640x480 LCD screen, including the HDMI VGA Controler Driver Board.
I purchased it via AliExpress. You find it here.
I took this one, because it perfectly fits the dimensions of the MCDU. And 640x480 is all you need, because it’s only text it needs to display.
Greetz