I signed up and it appears to be legit. I’m in Washington State. As others here have stated, there’s no QR code. But here in WA the state has created its own separate site to provide covid QR codes, so myirmobile not having it is no longer problematic.

Also at least in WA myirmobile shows other immunization records besides covid. It provides access to the state’s complete record and so includes for example my recent flu shot.