Sparkfun tutorial :
https://learn.sparkfun.com/tutorials
Not only does it sell a wide variety of sensors, boards, and parts, but it also has a vast amount of systematically organized courses. Think of it as an Adafruit competitor. In addition to this, DFRobot, Redbear Lab, SeeedStudio, etc. are companies that play a similar role, but the amount of information they provide is a little lower. Beginner Intermediate