OK, this is somewhat about AVR but more about RPi.
Thinking of a home project using a combination of RPi and an AVR. The AVR would handle the sensor interfaces and maybe interface to a LoRa module. The RPi would handle WiFi LAN connections, data display and system control. Yes, it can probably all be done in the RPi, but that is not what I know about.
Not yet very familiar with RPi hardware interfacing, hence this question: of all the interface channels for the RPi (WiFi, USB, BT, SPI, I2C, etc), which ones represent low pain and good development success rate, considering both ends?
My initial thought is that WiFi and BT both represent aignificant challenges at the AVR end. SPI and I2C seem to require a lot of fiddling with obscure code modules at the RPi end. USB is native at the RPi end and easily implemented with an FT232R at the AVR end. Is this a reasonable assessment?