After my own extensive testing, I have come to the conclusion that you SHOULD NOT use a Pico-W module with this LoRa module WITHOUT separation. This little board is my LoRa to MQTT gateway (via WiFi) for the Roverling project.
Wired like this, communication is good for 500+ meters line of site. With Roverling inside a large metal shed, and the base station 80m away inside and at the back of a timber structure, we get around -105dBm RSSI and an SNR of around -3dB. Excellent results.
Now, if instead you just stuck the LoRa module on top of the Pico-W, as it is designed to operate, and leave everything else the same, you will get a 10 to 20 dB drop in SNR as you start to go below -70dBm RSSI. This is only happens with the WiFi variant, if I use a plain old RP2040 Zero, good results again.
This is a massive difference, the Pico-W must generate so much noise as to swamp low level signals entirely. I would suggest, separate modules as far as possible, and to be sure I’ve even stuck a shield in between.
Important to note that the noise doesn’t impact transmitted signal from base station and in either configuration the RSSI and SNR measure the same at the remote end.