I was trying to find some references about this topic but I didn't find any, so I decided to post this question first before buying something that won't work. Does IoT Core supports this? If so can you give me a link "how" to communicate with devices in such way?
Serial Port Sample explicetly mentions the Raspberry Pi and the use of its on-board UART as "verified to work":
On-board UART (Rasperry Pi2)
The Rasperry Pi 2 or 3 has one on-board UART. See the Raspberry Pi 2 Pin Mappings page for more details on the GPIO pins.
UART0 uses GPIO pins 6 (GND), 8 (TX) and 10 (RX).