While I agree with the premise of your article, pointing to the 6th District as winnable by any Democratic candidate more to the left than Ossoff belies an unfamiliarity with the district.
The District is a wealthy neocon/neoliberal enclave and will not in the immediate future stomach a non-Establishment candidate. I grew up there to parents who still live there and may have been on the fence this go-round, but would never have gone for anyone further left/”non-mainstream" than Ossoff.
That will be a big challenge: contending with wealthy districts where even those who have historically voted Democrat vote for “safe” candidates.
I’m not trying to throw up hurdles, just trying to point out the challenge to start thinking about ways to address the challenge.