Okay, nevermind, after debugging pfSense I learned that in fact I226-V does support ALTQ.

Turns out I just had my LAN interface accidentally set to ipv6 DHCP mode, which created a gateway for it, hence the wizard detected all my interfaces as WAN, and it requires the inputted amount to not be higher than the amount of WAN or LAN interfaces, whichever higher, so 1 was higher than 0.

The error message is a bit misleading as a result though.

Seems to be working after disabling ipv6 on LAN. I really need to understand ipv6 better before I get into that anyway.