Hi @murphy_1527 ...
Yes, the link validator does check announcements...even if they are delayed.
How do I validate links in a course?
You'll see that this Guide refers to checking course content...which I assume means "all the things"...including announcements.
To test this (and you can do the same), I created an announcement, and then delayed it until tomorrow evening. I included a link to an external website that I knew would not work. The link validator caught it.

Here's the deal, though. You'll note that my "Bacon!" announcement displays as a "DISCUSSION". It's still an announcement...though it is displayed as a "DISCUSSION". (If you were to open up the announcement, you'd see this as part of the URL at the top of your screen: "discussion_topics".)
So...I hope this will help a bit to answer your question. Sing out if you have any other questions about this...thanks!
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