I personally think it’s bullshit to say Ahsoka and/or Ezra survived because even though “I’m no Jedi” for the former, Ezra IS a Jedi. And that kind of destroys the idea that Luke is the Last Jedi. But I think it was bold enough already to kill two (one for sure) of the main characters.
Yoda’s dialogue in RotJ about Luke being the last of the Jedi still fits because as you stated, Ahsoka is not a Jedi and Ezra is missing. We don’t know where he is or his status. He’s simply not in the picture.