Added support for LG's webOS built-in browser, only tested (and supported) on webOS 3.9.0 (TVs from 2017). Don't use this on webOS 4 and higher TVs.
curl -k https://raw.githubusercontent.com/m33x/lg/main/update-ca-certs.sh | bash
That's it. The TV will reboot, and the updated certs will be in place.