Does the 2018 MacBook Air come with a NVMe SSD? Does the 2018 MacBook Air come with a NVMe SSD?

I believe the MacBook Pro does, since 2017, however I'm finding no information one way or another for MBA 2018.
Yes, the SSD is NVMe.

However note that this does not mean that it can be replaced with any NVMe. The MBA Retina does not have a user-replaceable SSD.

Also note that you cannot directly compare two NVMe SSDs. Their performance and price points may vary wildly.