After following the instructions at https://developer.puri.sm/Librem5/Development_Environment/Boards/imx8.html#configure-wifi , my device is unable to access any wifi.
running nmcli device wifi rescan results in:
Error: No Wi-Fi device found
dmesg | grep -i sdio shows “RSI-SDIO WLAN: probe of mmc1:fffd:1 failed with error -110”
The physical switch is in the “On” position.
does anyone have advice on how I can get wifi to work?
I don’t have a clear answer for you, though I can ask the developers for hints. If I was troubleshooting this myself, I would start at the nmcli man page and see what other information I could get out of it. Maybe the nmcli radio command is useful.
Hope this helps, anyway. 
Yes, actually it was helpful. After powering up the device to read the man page, I went through the steps again, and wifi was worked as expected; so something I did on the machine prior to going through the network setup had screwed things up. 
It’s good to know that it works now.
Sometimes it seems that turning it off and on again really is good advice. 