Well, Andreyko has been friends with Brian Bendis since the 1990s. He's worked with him on Torso for Image, and when Bendis took over the Superman titles, Andreyko was given Supergirl. Before the pandemic, Andreyko was set to write a spin-off title for Bendis' Event Leviathan. So, that's the Bendis connection.
Andreyko also has a history of writing comics with strong female leads for DC. The aforementioned Supergirl is one example, others are Manhunter and Wonder Woman '77. He has experience in this field, so he would certainly fit in with Naomi.
And then, the same week that it's announced The CW has given Naomi a series order, Marc Andreyko resigns as a competitor from the Movie Trivia Schmoedown. He was co-champion in the Teams division, with a match in which he'd have to defend the title coming up soon. He's been a competitor for five years, a fan favorite, outspoken about how much he loved the Schmoedown, and he had to pretty much abandon his team mate Jeff Sneider before one of the most important matches. And the reason he gave was a job opportunity.
So, yeah, my guess is that job opportunity is with Naomi. It wouldn't be writing a comic book series, he's written comic books the whole time he was competing in the Schmoedown. So it has to be something bigger.
So, yeah, the timing of the Naomi announcement and Andreyko's Schmoedown resignation, Andreyko's history of writing female superheroes, and him being a guy Bendis calls on as a writer he trusts, that all seems to point to him being part of the show.