A pipedream
Implicit Conversions, the developer porting the PlayStation classics available with PS Plus Premium to PS5 and PS4, is “dreaming about” adding PS3 support to its proprietary Syrup emulator.
The emulator currently supports a wide array of retro systems, and allows said software to be updated with contemporary quality of life features, like Trophies. However, as part of a roadmap, it noted that it’s “researching and prototyping the possibility” of PS3 support.
It’s important to underline that this is all at an experimentation phase and may not actually be feasible. However, the fact that work is taking place is a positive to begin with.