Nonetheless, Hungary and Slovakia control over the half of ENTSO-E crossflow to Ukraine (pic from before the Russian invasion of 2022, it contains a couple of serious errors, e.g., misplaces Khmelnytskyi, but the grid graph remains the same).

So I'm inclined to think that they could weaponize these supply channels against Ukraine in the same manner as Putin and Zelensky weaponized Ukrainian gas transportation systems. The game can be played both ways.