Is that all you have about “redpine_91x” in your dmesg? You should have more.
You should see the redpine_91x module or something like it when you execute sudo lsmod.
Your RS116 firmware is old. You can upgrade it like this:
wget https://source.puri.sm/Librem5/redpine-firmware-nonfree/-/blob/master/files/firmware/RS9116_NLINK_WLAN_BT_IMAGE.rps
sudo mv RS9116_NLINK_WLAN_BT_IMAGE.rps /lib/firmware/
EDIT: Those were bad instructions. Upgrade the firmware this way:
sudo wget https://source.puri.sm/Librem5/redpine-firmware-nonfree/-/raw/master/files/firmware/RS9116_NLINK_WLAN_BT_IMAGE.FW2.5.1.11.rps?inline=false -O /lib/firmware/RS9116_NLINK_WLAN_BT_IMAGE.rps
Then reboot. (I think that Birch and Chestnut have a different procedure for upgrading the RS9116 firmware but I’m assuming that you have Evergreen.)