If you target consoles, you’re already on the lowest end hardware you’ll run on. It’s extremely rare to have much (if any) headroom for graphically competitive games. 20% is a stretch, 3x is unthinkable.
Then I would do most of the development work that doesn't directly touch console APIs on a PC version of the game and do development and debugging on a high-end PC. Some compilers also have debug options which apply optimizations while the code still remains debuggable (e.g. on MSVC: https://learn.microsoft.com/en-us/visualstudio/debugger/how-...) - don't know about Sony's toolchain though. Another option might be to only optimize the most performance sensitive parts while keeping 90% of the code in debug mode. In any case, I would try everything before having to give up debuggable builds.
It doesn’t matter. You will hit (for example) rendering bugs that only happen on a specific version of a console with sufficient frequency that you’ll rarely use debug builds.
Debug builds are used sometimes, just not most of the time.
