Earlier quoted context omitted.
So without a domain whoever owns the domain you're using can deplatform you. The result is dropped emails at that address forever. With your own domain, the registrar can pull a namecheap and cancel your country. The result is temporarily dropped emails while you transfer to another domain registrar. You can set the registrar to autorenew.
I de-googled last year but still use google domains as my registrar. It's just so darn cheap and includes DDNS. I've looked at alternatives and I haven't been able to strongly identify one I trust more than google (as strange as that sounds). How do other people pick a registrar that they trust?
There are DDNS scripts on github to update the DNS record. Picked gandi a very long time ago and have no complaints.