Yes there is no official annocement for vitalik as a supporter of ehf, but a picture of vitalik with one of the developer from ehf team. And in crypto world its enough to create some hype, its possible that vitlalik know EHF now cause he know one of the dev, and its a good point for the visibility.
Thats true! If he knews him, he also probably knows about the project. But its a complete other thing if he is supporting the project or not. We dont know until there will be an official announcement.
Even if they support officially, its possible they would not announce to public directly. I have seen some project which deals internally only, and not public