If follow by the book this is not only limited to hybrid. All other cars also have this clause. Anything you change that is not authorised by SC will void warranty. However, it is not executed to the tee. Therefore, SC usually close one eye.

As for your hybrid of adding double lock. It should be fine. It's just that the acc shop dare not do the job as they are not experience enough. You could probably go to another acc shop that have experience with hybrids.

Not that simple for pedal lock as it will tap into the car electrical system. But yeah this is debatable.

BTW, if TS is still around, what is your FC like for the car?