The key here is that this funding is for Ukrainian defense industry, it already has weapons systems capable of striking deep behind Russian lines. The US simply isn't going to budge on allowing western weapons to be used, their policy is looking towards relationship reset following the end of hostilities, they don't want Russia to lose since that could start a more prolonged cold war and period of instability. Ukraine will need to use it's own systems, fortunately it is becoming more and more capable by the month.

This is from memory so don't take it as fully accurate, but I believe Ukraine was something like the world's 6th largest arms manufacturer prior to the 2014 invasion of Crimea. They know how to make things go boom.