Lo-Fi, unobtrusive overlays for 16:9 retro gaming handhelds such as, and tested on, Retroid Pocket 4/Retroid Pocket 4 Pro. It also includes pixel grid effect to better mimic GBA display. Tested for 16:9, 1334x750 (750p) resolution. For use with RetroArch. This will probably work on any 16:9 device such as Odin 2 or the Retroid Pocket 5. However, I have neither so I cannot test it.
Attributions: Jeltr0n, cizia64
Apply using RetroArch Quick Menu
Quick Menu -> On-Screen Display -> Overlay Preset
Overlay Opacity 1.00
To set it permanent,
Quick Menu -> Overrides -> Save Game Overrides OR Save Content Directory Overrides.