Most RetroArch users rely on community-curated BIOS packs hosted on archival platforms. Search for:
Where to look safely:
Much like the Sega CD, playing CD-based TurboGrafx games requires the system card BIOS. bios files for retroarch ps vita link
If you legally cannot dump a PS1 BIOS, consider: Most RetroArch users rely on community-curated BIOS packs
However, for Sega CD and Neo Geo, original BIOS files are mandatory. Where to look safely: Much like the Sega