I think it was retired General Petraeus that said the reason they're not getting M1 tanks is because they don't have the infrastructure to repair them. They'd have to fly the tanks to Poland to repair them, it's impractical. Not to mention the training.
I imagine the same problem exists with aircrafts.
Israel could share their missle shield technology, though I imagine similar issues would exist there too.
The good news is the Ukrainians acquired more Russian equipment, which they already know how to use, in Kharkiv than they have from the allies in the entire war. Stopping the west from supplying weapons has lost some significance, if only in the short term.