it’s not security, just obscurity

IIRC for my setup it’s a bit of both. My DNS API key is scoped to only handle the specific subdomain updates instead of my entire DNS account.

I still use a wildcard for that subdomain for non-kubernetes systems, but the cert plugins for kubes is excellent at handling a LE cert per lan fqdn.

You don’t need to register a local CA

This was my biggest reason to move to Let’s Encrypt. I have a Hashicorp Vault instance in my homelab for secrets and I tried using it for an internal CA (like how the lab at work is set up), but trying to get on every device and add the full Vault chain to each individual system’s trust store was massive pain in the ass.