Yes, this works if your RSS server has its own DNS record that you control, and is essentially what the Domain Handle -> DID indirection gives you in AT Proto.

What Bluesky and AT Proto in general do is make it easy for people to either get a domain (a *.bsky.social subdomain) or use their own as their handle.

And AT Proto also lets you change your domain while preserving your identity, since the actual identity is a DID.

That makes it very easy to move your data and your handle around and not lose followers. If you change your RSS server's domain name, your subscribers don't come with you.