Anteaters can be seen to dig in Leafcutter Ant Chamber blocks and convert them into Coarse Dirt, but do not produce any of the items suggested in the Animal Dictionary, or indeed that appear in the actual loot table (accessible with commands as alexsmobs:gameplay/anteater_reward). If the Chamber has a fungus level of 5 they will dig up the expected Gongylidia, but that's it.

Video shows only a brief test with Chamber blocks at fungus level 5 for the sake of file size, but I have tested over multiple hours and with various fungus levels with similar results. The setup of the anthill, such as being naturally generated, having Ants present, or having one or more Anthill blocks above the Chamber blocks, also seems to make no difference.

Mods:
Alex's Mobs (1.22.9)
Citadel