Can't help you on the first question I don't have a ps2/ps3 anymore. In the vita case, there is emulation for psp.
As RetroArch, it is using duckstation for the ps1 emulation. That is the emulator.
OK, but why do Project Eris and AutoBleem come with Retroboot when they already run PS1 games without the latter? What if some users don't want Retroboot to begin with? How can PSC's Retroboot be updated?
It seems AutoBleem's Retroboot has 4 PS1 cores.
Does AutoBleem's/Project Eris' Retroboot have higher PS1 game compatibility than the stock PS1 emulation and do PSC's PS1 game compatibility lists found on the internet regard the stock emulation or Retroboot?
It seems FMCB is compatible with all PS2s but it only works on the last PS2 Slims if using a modchip with a program called HWC's OSDSYS Launcher and FDVDB is compatible with all PS2 Slims but not with all PS2 Fats. Fortuna could be used in all PS2s (including in PS2 Fats incompatible with FDVDB) but only after finding a way to transfer uLE/wLE to a MC.
I got IGR working but in a different game. It seems it's not compatible with all the PS2 games. I set IGR to run OPL since it runs wLE by default.
EDIT: Now, PS2-Home is redirecting to the official OPL GitHub repository when downloading the latest OPL Beta version instead of downloading its former Daily Build and ifcaro forks and it stopped releasing the latter two. Apparently, I had bad luck to access PS2-Home at the time. Also, the official OPL's GitHub repository says anyone can contribute improvements to OPL due to its open-source nature so how did PS2-Home steal the project like I was told in PSX-Place?
EDIT 2: A GitHub user (grimdoomer) released OPL
forks which support + 2 TB exFAT/FAT32 internal HDDs/SSDs/SSHDs and multi-BDM devices. Didn't he steal the project like PS2-Home, then? The internal HDDs/SSDs/SSHDs can be formatted on the PC with the GPT or MBR partition styles. The official OPL versions only support the APA partition table and wLE can format the internal HDD/SSD/SSHD to it (the partitions it creates are in the PFS file system, which is a proprietary file system used by Sony).
EDIT 3: I updated AutoBleem and noticed Retroboot now has a new UI and has more than 4 PS1 cores.
EDIT 4: All the PBP games I tried on the PSC had a black screen or froze on the logo and all the Retroboot cores I tried couldn't run them as well.
EDIT 5: I downloaded PBP games converted by PSX2PSP from BIN/CUE, tried them and they didn't have problems. I was told it's normal for PSN PBP games to not work on the PSC since they're encrypted and some have audio in Sony's ATRAC3 format and AutoBleem doesn't support encrypted PBP files or ATRAC3, as well as all the Retroboot PS1 cores I tried.