I would think the recommendation of Ciro Salvo says it all! Is this available in the US?
Absolutely yes, it is a great product and yes, Ciro Salvo recommendation is definitely positive.
Not only, if you go to their website, you can also see that this flour is approved by AVPN, Verace Pizza Napoletana, not to be confused with APN (pizzaiuoli napoletani which is not a real association but just a marketing tool of another flour producer which I'm not even going to mention).
I did not know of Viola, I definitely know that in the NY area Ranieri Food is the usual distributor for 5 Stagioni, so I'm pretty much sure they will soon have also the product for Neapolitan Pizza.