I’ve done a psp overlay if you use the retroarch core only
Can’t upload the config file as it won’t allow that extension but just create a .txt file then change the extension to .cfg open the with a text editor and type these and save
overlay0_overlay = psp1000-1.png
overlay0_descs = “0”
overlay0_full_screen = “true”
overlay0_name = “overlay0”
overlay0_normalized = “true”
overlays = “1”
overlay0_overlay = psp1000.png
overlay0_descs = “0”
overlay0_full_screen = “true”
overlay0_name = “overlay0”
overlay0_normalized = “true”
overlays = “1”