Zigbee for dummies?

I’m new to home automation, currently only have experience with Shelly wifi devices.

Trying to understand Zigbee devices, I’m getting into lot of doubts. In example:

  • In this thread about changing behavior of a smart button: I’m trying to understand if I modify a button push and long push behavior, those modifications will require ZHA/Z2M/… to always work , or those changes to the behavior are saved in the device so they keep working even if Home Assistant is down.

  • This is the only explanation I have found about Zigbee binding, but I’m having problems to understand it fully. It says how to bind devices, but no configuration at all? So, how does you made device A send the correct order to device B? Also, all examples I find are about binding buttons/remotes to switches/lights. Can’t I bind two switches together, in example two Sonoff ZBMINI-L , so if the physical switch is pressed in one the other one gets also triggered too?

I suppose there must be some good information explaining this Zigbee 101 stuff, but can’t find it. Any suggestion of what to read to try to get a better understanding of all this?