-create 2 internal subnet objects address FGT1LAN and SW2LAN.
-create a VPN tunnel
-create 2 policies rules
-create static route to SW2LAN through VPN tunnel
-create 2 network objects SW2LAN and FGT1LAN
NOTE: FGT1LAN is in VPN Zone
-create a VPN/Settings
You can try ping from PC1 to PC2 now