When I used RetroArch on my PC, the libretro core was Mednafen. When it loaded a game, I got that classic PSX boot screen. The PCSX-rearmed core on RetroPie, it doesn’t show it. I feel that is really missing some of the nostalgia from playing PSX games. Is there any way to get this using PCSX? I’ve tried a couple different BIOS files, and that doesn’t seem to make a difference.
How anxious are you to test it? I can try to make a module of https://github.com/libretro/beetle-psx-libretro which is a port of the mednafen emulator you speak of. Can’t guarantee the performance as the current one is optimised for arm, this may not be.
As far as the prelaunch video instead of an image, you’d have to recode runcommand to call omxplayer and your video. I doubt we’ll integrate video support for runcommand, likely something like that will just have to be done manually.