how can I configure my wireless to use a different ISP rather than the one used for my LAN.
You can use SD-WAN rules. You can find additional info here:
I have created the SDWAN profile and routes but nothing positive yet.
do I need to creat a NAT rule for the my Wi-Fi firewall rule to a specific outbound port?
There is a Default SNAT rule that masquerades all outbound traffic WAN interfaces. Enable this rule if it's not enabled already.
ok. Thank you.
You can read about this here: community.sophos.com/.../routing-in-xgv18-with-sd-wan-pbr