When you are personally affected by the harrowing prospect of a child of yours or a child relative of yours being sexually abused by their abusers and the police turn around and say 'sorry, there is nothing we can do to catch the abuser because we are unable to get into the end to end encryption the abuser was using, the right to privacy debate no longer has any relevance.
From the various UK investigations into child abuse it's a fact that abusers use devices that have end to end encryption to avoid detection and to avoid having their messages exposed because without enough evidence, the CPS (Crown Prosecution Service) will not prosecute and the abusers know this. It is an extremely tough call to make, the right to privacy or the right to protect children.
I have young nieces and nephews. Would I give up my right to privacy knowing that in doing so it would help keep them safer and make it easier to find and arrest child abusers? Yes, of course I would.
Is banning e2e encryption really going to keep your niece & nephew safe? All the surveillance in the world cannot and will not replace involved parents & family, and will likely just create many more paths for your niece & nephew to be harmed now and in the future.
I have a niece & nephew I love dearly, too, but we rely on knowing where they are, what they're doing, who they're interacting with, and most of all, raising them as *thinking* humans who know what is and is not appropriate for anyone (family included) to ask of them and do to them rather than hoping the government will do the parenting/extended family job for us.
The research and empirical data of prevention of sexual abuse is clear: if you're relying on surveillance, you failed years before elsewhere (you can do everything right and still be a victim, not saying that, but I am saying that the numbers come way down when you rely on that rather than abdicate control to a government agency that does NOT have your best interests at heart). Teach children about their bodies, boundaries, and be active parents/family. Bad things may still happen, sure, but show me any perfect solution for anything...