Does anyone know how to play backups on a PS2 without a chip, or needing to open it?

you can do a knife or cog method with a gameshark look at the PS2 section and search for those terms or look for cousinfizz's post on the subject

I dont recommend stabbing your Ps2 with a knife but its up to you

YOU CAN ALSO USE AR2. YOU CAN PLAY BACKUP CD'S AND DVD'S