I’d expect vesicants to work on zombies (though once it disperses they’d heal and get back up, they need pulping). AFAIK that is not going to work on either fungals, triffids, or ants.
The only thing on the list that seems like it would work on ants would be Carbon Monoxide in very high concentrations, though there are many, many other options for that, though the quantities needed may be problematic.
I think there’s a lot of room for making things interesting by having different enemy types vulnerable to different weapons.
In addition to the various highly weaponized options for delivery, you could target unintelligent enemies by installing a poison gas generator in an area near targets, or do something to attract them.
For example when raiding a zombie area, you could don a gas mask, then mix up a batch of bleach and ammonia (even better do it in a house), then run outside and get the attention of as many zombies as possible, then lead them through the house.
Another neat option would be to set this kind of thing up to be remote triggered, and then only use it if you get in trouble, triggering the gas production as you approach the house with a horde in tow.