So Ukrain can’t use the cluster bombs on any area they intend to occupy or traverse. They can’t use them on trench lines, they can’t use them on fields they would need to drive over.

Combat demining equipment exists^1^, and that equipment doesn't care whether it's Russian cluster munitions, Ukrainian cluster munitions, Russian mines, or Ukrainian mines -- both sides have used all of that, and with "mines" I mostly mean artillery-deployed stuff.

Those areas will have to be gone over with a fine-toothed comb anyway to demine them. A couple bomblets more or less don't make a difference in that regard and meanwhile those munitions can help Ukraine break Russian defensive lines much faster and bring this clusterfuck to a reasonable conclusion quicker (i.e. Ukrainian victory).

The drone ammunition stuff is true, too, but I guess the priority will go to using them as intended as you can drop a lot of stuff from drones.

^1^ Among other things Ukraine has at least 20 GCS-200, the Swiss are shy when it comes to sending weapons but have no issue with that kind of stuff.