Well in the end Giannis Antetokounmpo was chosen with...Antigoni Drisbioti.
Apparently, it was agreed that Giannis would be the male flag bearer and there was a vote between Drisbioti, Sakkari, Evangelia Platanioti, and Margarita Plevritou and Drisbioti won the vote.
I think it's very random and even some of the other voting options were random. Girls like Teltsidou, Kaztouraki, and Gkountoura who have chances for medals would've been better in my opinion. Or Tzengko even but I guess having two children of immigrants as the flag bearers would've seemed too political.
Sakkari is ranked higher than Drisbioti, is more well known, was closer to winning a medal than Drisbioti in the past, and has a better chance of winning one in Paris than all the others except maybe Plevritou.
Drisbioti gave a sob story to the Greek media a few years ago about not receiving support (which I agree with btw) and she became known and it became trendy to support her (I like her too but think it's excessive, and people probably don't realise that most of her big medals were in a non-Olympic category), but she is good at walking which she will need to do at the opening ceremony so