I have recently finished building kit with 8" screen. A lovely kit, right down to the beautiful packagaing. Thanks, Pimoroni! :)
I don’t know if most people run RetroPie. I so far just want to use Picade to run some home-brew Python//Pygame and maybe C/SDL games. The Python thing is to resurrect some 2D retro games I did a year or two back with a Code Club in a primary school.
Anyway, at the moment I am running standard Raspbian desktop. I followed the advice to put hdmi_force_hotplug=1 in boot config. Worked fine and booted to desktop. Looks cute! The driver for Picade Hat installed fine too. After a while I realised display was not running full resolution - only 640x480 I think. Suppose that makes sense as safe mode for not detecting display powered from USB, Eventually I ended up with this in /boot/config.txt:
which gives native 1024x768 and looks nice and crisp.
Maybe I should just try running Raspbian lite, without desktop, but this has got me started. Good luck to fellow Picade builders!