There's a new exploit for the PS2 that will allow you to run games from other regions as well as backup discs. It only works on certain revisions of the PS2. As far as I can tell, you simply run an ELF and patch the PS2 at which point it can run retail PS2 discs from any region, as well as retail or burned PS1 discs from any region. With a few extra steps, you can get it to boot PS2 burns by going into uLaunchELF. So all you really need is FMCB and the MechaPwn ELF.
So if I'm reading everything correctly, after you patch the PS2 you can load retail PS1 or PS2 discs from any region as you would any other retail game disc. You can load burned PS1 discs as you would normally load a retail PS1 disc disc. But for burned PS2 discs, you have to go into uLaunchELF and launch the disc from there.
https://www.retrorgb.com/mechapwn-exploit-for-ps2.html
My PS2 phat has the front link port, so I guess that means it's not compatible. But it looks like my PS2 slim is compatible, so I'm definitely going to check this out! I had bought a mod chip for my slim, but I haven't installed it yet because I was dreading how tedious it is. But I guess if this new hack works then maybe I'll put the mod chip in my phat instead. Generally with my phat I just load PS2 games from the HDD, but occasionally it would be nice to boot burns if I just want to quickly test something (the process to get games onto the HDD Is a pain in the ass).