A piece of Good Omens show fanon that never fails to irritate me is "Aziraphale and Crowley were useless!" The scope of their supposed uselessness changes -- for some fans it's the whole season, for some fans it's the airbase situation -- but either way, canon doesn't support it.
You can't take any of the humans, Aziraphale, or Crowley out of the airbase situation and end up in a win scenario:
Anathema: gets Newt into the command center
Newt: stops nuclear annihilation
The-Them-minus-Adam: deal with three of the four Horsepersons
Shadwell: arguably the most useless, but still the source of the Thundergun and the reason Madame Tracy is hosting Aziraphale
Madame Tracy: hosts Aziraphale and (crucially) stops him from murdering Adam
Aziraphale and Crowley: pep-talk Adam, and stop the angel-demon war that would otherwise decimate Earth
No, there's a point being made here, and not subtly: no one can do it alone, for just about any value of "it."
That's another reason the finale of the finale is a big fat fail. It's vastly unfair, unbalanced, and counter-thematic for Aziraphale and Crowley (especially if you think of them as what TV Tropes calls "The Dividual") to be cornered like rats by God and Satan, without a single ally available.
They need friends (even beyond one another). We all do, pretty much. They need humanity. We all do! And they don't deserve to face the two Big Bads (sorry, everybody who trusted GO!God or wanted Her redeemed; She is as horrible as ever, the one consistent element across the entire show) alone, as much as they've done for humans.
It was a wretched thing to do to them, both Doylistly and Watsonianly.