NodeMCU burned, did I something fundamental wrong?
Yes, you did something fundamentally wrong.

The component that blew up is a diode.  It is designed to protect the USB from voltage being injected into the board.

That diode can handle an absolute maximum of 1A.

Any fault on your LED strip connection (a short to ground) will cause that diode to vacate the premises. As yours did.

The purpose of the VIN pin (as the label suggests) is as a voltage input. It's not really designed to provide power to other devices, especially as the ESP8266 itself can take more than half that 1A power budget when communicating.  You should not use VIN for powering anything more than maybe a couple of low power sensors. LED strips are a big no-no.