How compatible is the Xiao to an Arduino e.g. Nano?

Products & Technology XIAO
24

Serial.begin() goes in Setup(). Serial.println(func); has 2 underscores on either side of func The forum sees fit to strip them. Either put the 4 underscore or just use Serial.println(“This is the message to look for”);

Is pin 2 the same as A2/D2 ?