How many phones still support 2G? If its a lot I suspect a security patch or firmware update could fix that. They do link to this [1] for Android, a setting I do have.

They then push the scam messages, which contain links to fraudulent websites, to the connected phones

Seems like disabling non-HTTPS could also be done through an update. Plenty of scammer sites have legit DV certs though.

[1] - https://source.android.com/docs/security/features/cellular-s...