The M2 Mac "Slow SSD" Issue Explained (in 6 minutes) - YouTube
Amazon.com: 256GB SSD Hard Drive for Apple MacBook Pro Air 11" 13" 15" A1502 A1398 A1465 A1466 (Late 2013-2015) / OSX Sierra/Mac Pro A1481 : Electronics
Photo tutorial: Upgrading a MacBook Pro with an SSD