And it may be flamboyant, but I don't think that makes it some gay stereotype as I've seen some argue. It fits a suave, makes-the-ladies swoon dancer about as well, just with a silly prancing run thrown in. It's focus on dancing, colorful appearance, etc. are all more common as male bird traits for wooing females, or just for mutual wooing when the sexes look the same.
Something I want to point out is that it looks flamboyant to North Americans and many Europeans because there isn't anything quite like it in the culture, but there are plenty of male dancers like this in Brazil, who are not seen as flamboyant or stereotypically gay, but just...male dancers. Quaquaval's design, while it looks effeminate to those unfamiliar with Brazilian culture, shows that Game Freak did their research and made something true to its origins without fear of it looking strange to others. And as you said, it's common among birds for the males to be flashy and showy and the females be drab and dull (whereas it's the other way around for most mammals and reptiles).
It reminds me a lot of how people complained about the Viking-themed Perrserker last generation, that people didn't understand why Galar would have a Pokémon themed on housecats and Vikings. Cats were important parts of Viking voyages and were treated as respected crewmembers, and the British Isles not only had a long history with Vikings, a lot of Viking ancestors still live on the British Isles to this day.
I'm certain that Skeledirge is the one winning all the polls though, mainly for the sole fact it's the "not-humanoid" one of the three. I'd be more interested to see which one is most popular in Japan though, because that will probably dictate the marketability factor of these starters.
Generally, it's the base forms that the Japanese fans go for (not the ones doing PvP, mind you, but the ones who just like the designs). There are a few exceptions, like Blaziken over Torchic or Greninja over Froakie, with Braixen being the one middle stage that's more popular than the base or full form, but for the most part, you'll see the base forms marketed the most. Expect to see WAY more merchandise of Sprigatito, Fuecoco, and Quaxly than Meowscarada, Skeledirge, or Quaquaval (though Floragato might become the ensemble darkhorse due to it being the only yo-yoing Pokémon so far).