You have three choices: Apple (BeetsTech), OWC or Transcend. The BeetsTech has a very good writeup detailing the different SSD’s.
The word SATA gets a bit muddy as it implies to factors the physical interface (the connector) and the type of protocol used across the interface (AHCI) which is always used with the SATA connector. Today we have a new type of connector for simplicity sake we’ll just call it an edge connector. The first version was called mSATA (for micro SATA) then Apple took the idea of the smaller connector and moved forward designing a still smaller interface as the standards group was taking to long they went forward with their own connector and protocols. Apple as it turned out didn’t venture far it whens with it’s own connector and used the AHCI protocol which is clocked a higher rate than what the M.2 standard was defined at. As Apple was part of the standards group the standard does follow Apples direction but is not the same! Here is the standard laid out in block form:
The Red line is what a SATA interface would use and the Orange line is what your MacBook Air uses.
So as you can see even the standards can be confusing! And to add to it Apples own custom SSD’s don’t use the same connector at least they use the same protocols, but in SATA boards the clocking is different.
Thats why its best to stick with the big three and not try to fit in a M.2 standard SSD into a system which while similar is not the same as what Apple has done.