As to making an emulator for Sony Playstation by reverse engineering, here's some interesting court cases you might want to look at:
https://freedom-to-tinker.com/2003/09/04/ruling-garage-door-opener-case/
https://freedom-to-tinker.com/2003/05/30/dvdcca-v-bunner-california-supreme-court/
https://www.wired.com/2017/06/impression-v-lexmark/
These decisions are based in the United States.
The DVD one I think is the big one. IANAL, but I think that if you own the actual disk for a PS4 game, and your console breaks so you can't play the game anymore, the way that I read it is that you are free to use a competitor's product to play the game...hence the interoperability with the garage door opener case. You can even make repairs to it, hence the Lexmark one, if you know how to do so. But, I could be wrong. My advice is to consult with a lawyer who practices within your part of the world to be sure.
https://freedom-to-tinker.com/2003/09/04/ruling-garage-door-opener-case/
https://freedom-to-tinker.com/2003/05/30/dvdcca-v-bunner-california-supreme-court/
https://www.wired.com/2017/06/impression-v-lexmark/
These decisions are based in the United States.
The DVD one I think is the big one. IANAL, but I think that if you own the actual disk for a PS4 game, and your console breaks so you can't play the game anymore, the way that I read it is that you are free to use a competitor's product to play the game...hence the interoperability with the garage door opener case. You can even make repairs to it, hence the Lexmark one, if you know how to do so. But, I could be wrong. My advice is to consult with a lawyer who practices within your part of the world to be sure.