if you don't mind change your pineapple default ip for while, you can then enable internet connection sharing from your Mac WiFi adapter to the NANO USB adapter, you apply the correct firewall rules on your Mac to make everything work between the two interfaces, in my case the NANO ethernet interface is en4.
uci set network.lan.ipaddr='192.168.2.10'
uci set network.lan.gateway='192.168.2.1'
uci commit && reboot
then you can sharing
#!/bin/bash if [ "$(id -u)" != "0" ]; then echo "This script must be run as root." 1>&2 exit 1 fi sysctl -w net.inet.ip.forwarding=1 pfctl -e echo "nat on en0 from en4:network to any -> (en0)" | pfctl -f -
works for me.