Hi there, Is it possible to upgrade a early 2015 13inch MacBook Air ra

Yes, the Blade SSD can be swapped out, here's the guide Sostituzione SSD MacBook Air 13" versione inizio 2015 as to what to use your system offers a custom Apple PCIe 3.0 x4 interface. You can use a pin compatible drive from OWC or Transcend or use an adapter to convert the custom interface to a M.2 interface to plug in an M.2 drive. Depending on your use you may encounter issues with some of the M.2 drives so be careful on who’s you use and of course backup often.

I recommend to use a Sintech Adapter & a Samsung 970 EVO Plus SSD (With Firmware 2B2QEXM7 or 4B2QEXM7 and you shouldn't have any issues. I have been running this setup for over a year and so far it has performed perfectly.