What type of wired external VLAN capable Ethernet device are you trying to extend these VLANs to?
Because most VLAN capable Ethernet devices typically need to have a native untagged VLAN since native VLAN mismatch could cause the tagged VLANs not to work on the external VLAN capable external Ethernet device.
Also, if all these IOT devices are wireless and you don’t have any external Ethernet device that is VLAN capable, then I would just assign the specific IOT wireless network to the specific IOT network interface that is assigned to the specific firewall settings I wanted that wireless IOT network on.
However, if you do need to extend the networks to an external VLAN capable device like a managed mini-switch, then here’s an old post where I included some screenshots of how I extended VLANs out to my managed VLAN capable mini-switches.