As you know, the annotations are gone since January 15, 2019.
As I am a frequent viewer of the DataHoarder subreddit, I saw that they’ve been archiving annotation data from 1.4 billion videos. That’s crazy!
You can use this Firefox extension (works directly from YouTube servers) or this github thingie or even https://dev.invidio.us/ (if you don’t want to download addons) to restore the annotations!
Also, “If there is enough interest, an annotation creator can be made.”
Pretty exciting stuff! So if you’re interested head on over to this Reddit post by omarroth for more information.