[2019] Secret Lair -- Sleeves NOT exclusive?!?

Correct, the Secret Lair sleeves are not exclusive to the Secret Lair drop itself. It will be a while before you see them in the MTGA store though.

The Secret Lair cards are specific to Secret Lair, though. There are no plans to make them available outside of the 24 hour window that they are sold in. Here's the article that gives you details.

They will not be available on December 12, sorry about that! It will be much later.

@Garth:

A month has passed. When do you plan to make them available for purchase?

I don't have a date yet, sorry!