This feels very interesting as an item, but it really depends on what it can affect. (I don't think it should affect ults as that may be too strong against some heroes so I won't include them in the list below)
Here we got: Doorman Doors, Infernus Trail, Talon Traps, Holliday Jumppad (And barrel too could fit in), Ivy Kudzu?, McG Turret and Wall, Paige Dragon?, Paradox Wall and Bomb, Sinclair Assistant, Vindicta Stake, Viscous Cube? etc...
Abilities suffixed with a question mark here are up for debate, it very much depends on if you consider stuff like ground effects to also be constructs which could expand the range of things you can nullify.
The issue here arises where a lot of abilities sort of tether on the edge of being considered a "construct" or not and it really depends on what definition you wanna pick here.
If you want to go pure constructs, as in objects that you can collide with or that are marked as entities (like Turrets), then you have a very small selection of abilities to deal with.
Personally my biggest gripe with this item is how there isn't really a good definition for what these types of abilities should be, some people argue about which abilities should be targettable by slowing hex already.
As you said already, T3 would be better for this item but I wouldn't include a T4 upgrade if you're doing that, I wouldn't deem that too necessary.