Truly being honest, I think CSAM scanning of private comms is ineffective in the long term anyways. Pedophiles aren't stupid, you'll drag a bunch at first but the networks will be reestablished and sharing will be done via sneakernet.
The primary focus should always in preventing the creation of CSAM.
- Comprehensive Sex Ed starting young so kids can identify grooming and seek help from a trusted adult, even if abuse comes from a family member.
- Fixing schools in general so homeschooling isn't as attractive for parents. Keep a tab on home schooled children and identify social isolation.
- Bigger resources for actual honest to god on the ground investigations.
To be clear I'm not saying that homeschooling = child abuse, simply there's a lack of the mechanisms to detect it in homeschooling settings.