PCSX2 is an open source PS2 Emulator
Similar to this, you should know that with a network adapter and a hacked memory card, it's possible to play backup PS2 games from a NAS. However, you will have to downgrade your NAS's security to allow SMBv1. And not all games run smoothly over the network (nor do all games run smoothly off hard drives, solid state drives, USBs, or SD cards, which are also options). If you have the architecture and want to future proof your PS2 (lasers are dying fast), it's worth an afternoon getting it running. Keywords to get your started: OPL; FreeMcBoot.