This is a really useful discussion for anyone trying to get PSX games running through LibreELEC. The BIOS part can definitely be confusing for beginners, especially when RetroArch, RetroPlayer, and different emulator cores use different system directories.
I’ve also put together some basic information about PS1 BIOS and the setup side of PS1 emulation here: https://ps2biosonline.com/download-ps1-bios/
It would be interesting to hear from others using LibreELEC today — do you still prefer RetroArch for PSX, or have you found RetroPlayer has improved enough for your setup?