Some carriers do, some never did, and some did but gave up. In the end if they want wide deliverability they’ll have to connect to Google’s hubs (servers).
It is annoying that Google doesn’t provide an API for RCS as they do for SMS and MMS.
Keep in mind that you need backups perhaps moreso than you did when using OneDrive - 3-2-1 being robust without going crazy.
Ditto VPN vulnerabilities. Belt and suspenders can help though if a remote is compromised likely all the things it uses will be, if not immediately then eventually.
1.1.1.1 does no filtering. 9.9.9.9 does, similar to 1.1.1.2. To skip filtering use 9.9.9.10.
I expect they think that a significant percentage of people that have Internet also have a smartphone. They probably aren’t far wrong.
And Samsung gave up.