Yeah that’s right. For a whopping one time purchase of 250$, you get a lifetime license for a @linux.com domain as an email alias/forwarding only. You cannot send emails from this. You can contact support to check if the alias you want is available too.
Imagine this on your CV. It is the ultimate flex.
The biggest thing to remember here is that sending FROM your linux.com vanity address probably won’t work well. Yes, you absolutely can set your “mail from:” address to anything you want, but without corresponding SPF or DKIM records in the linux.com DNS server (which you can’t control and they won’t do), most major email providers will either send your messages to spam or outright reject them.