AM update: What's still left to count, and why hasn't a winner been called? https://www.nytimes.com/2020/11/07/upshot/election-count-remaining-biden.html

In Pennsylvania, I can think of two possibilities. One is that the desks are waiting for Biden to clear the .5 point recount threshold. That's a stated AP position.
If so, Biden could be called... at really any point, as his lead is now up to .43 https://www.ap.org/en-us/topics/politics/elections/how-we-call-races

Another possibility is the provisional ballots, which are a little murky so far if you're looking for 1000% certainty. That said, all indications are that they break Democratic: there's too much in Philly and Allegheny, and the early reporting in latter is that they're D+50

In Nevada... I don't know why there's no call.
The remaining voters are split between mail and same day registrants. The former have been two-to-one Dem. The latter are D+1 by registration, per state figures. This one is over. I don't know why there's no call.

In Arizona, Trump continues to gain on Biden. At this pace, he won't over take him. But he could close to within .5 or so, and there's enough left that it's hard to 1000% rule out the possibility he can't win the rest by 20, without better data.

In Georgia, don't expect a call until after the recount. But there's no real vote left for Trump to make up his deficit. The provisional ballots are Biden so far, late overseas ballots are not going to help Trump materially (if at all), and there might be straggling mail