OP here. To follow up it took about 2 weeks to get a visa using a NIE once the forms were in the au pairs hands. The US Embassy in France was very helpful and efficient.

Cultural Care was the biggest impediment (only mailing visa forms to Europe twice a week, not proactively providing host family with au pair virtual training dates, only allowing travel to US on Fridays because otherwise someone would manually have to request the flight). If considering an NIE be wary of the au pair agency used.

Highly, highly variable, even from a single country! I'm in a FB group of physician moms were it is easy to compare notes and super helpful to know what countries to avoid (eg Thailand and China near impossible and one point). It's been all over the place. We finally got an AP from Colombia on an NIE 6mo ago, but it was after several cancelled embassy appointments for her. I know on her end there was a social media group of Colombian APs seeking a visa with NIE, I think she probably learned some helpful tips there and stirrings of when the Embassy seemed to be granting / not granting the visa.

We are two physicians directly involved in covid care of patients and our au pair with NIE got denied anyway. It's all a crap shoot so have a ready to go back up plan.

NIE visas are prioritized so they are quick. Check with the agency directly-they have up to date information on it.

Has anyone been successful using a NIE to get Visa for au pair arriving from Europe? If so how long did it take for the au pair to get a visa appointment and then how long did it take after the appointment to get a visa. We are in healthcare and have been told we have a very strong case for a NIE to be approved (but know that even with this it’s slow process just trying to figure out how slow it is). Thanks.