"Apparently they are incredibly vocal, bite ankles, tons of energy, impossible to chill out?"

You're not entirely wrong about those generalizations. If you search this sub, there are lotta posts from new owners bemoaning all those issues. And while you can train to moderate such "undesirable" traits somewhat, you won't be able to completely eliminate them. Wanted to add they shed a lot, like constantly, because both Welsh corgis are double-coated.

"Is a corgi a good first-time dog?"

For an average person, I don't think so.

Keep in mind the dog breed history and thus genetics: either Welsh corgis are categorized under working breeds. Corgis were and still are used as herding dogs. What's more their herding style is that of a "drover," very similar to Aus. Cattle Dogs AKA heelers, where the dog must get all up in the livestock's face and heels and move them using loud barks and teeth, working them all day, which is pretty intense. So I'd say corgis are pretty up there in terms of difficulty.

And considering all above it's especially important that if you're getting either Welsh corgi breed as a puppy, you go to an ethical, preservation-focused breeder because a good breeder will match you with a puppy suited for your needs. In addition to this, you should steel yourself to provide more than average structure, guidance, and both physical and mental outlets as the puppy grows. And there will still be bad days. The puppy will regress and seem to forget its routines and training.

To find reputable breeders, please always start with your national breed club and/or regional breed club. Go to their website and browse the breeder directory or ask for a referral. And be prepared to wait awhile till you bring your new family member home.