The US military stockpile is staffed by Americans, not Ukranians, and there's no political will to transfer some of the really expensive stuff which requires extensive training like F35s. The transfers of Patriot anti-missile batteries, HIMARS, Bradley vehicles etc have been extremely effective in pushing back the Russian line of control from the initial invasion, but now it's a nasty question of assaulting well defended positions without air superiority.

https://crsreports.congress.gov/product/pdf/IF/IF12040

• 39 High Mobility Artillery Rocket Systems (HIMARS);

• 12 National Advanced Surface-to-Air Missile Systems (NASAMS); 1 Patriot air defense battery; other air defense systems; and 21 air surveillance radars;

• 31 Abrams tanks, 45 T-72B tanks and 186 Bradley infantry fighting vehicles;

• 300 M113 and 189 Stryker Armored Personnel Carriers;

• 2,000+ Stinger anti-aircraft missiles;

• 10,000+ Javelin and 90,000+ other anti-armor systems;

• Phoenix Ghost, Switchblade, and other UAS;

• 198 155 mm and 72 105 mm Howitzers and artillery;

• 227 mortar systems;

• Remote Anti-Armor Mine (RAAM) Systems;

• 9,000+ Tube-Launched, Optically-Tracked, Wire- Guided (TOW) missiles;

• High-speed anti-radiation missiles (HARMs) and laser- guided rocket systems;

• 35,000+ grenade launchers and small arms;

• communications, radar, and intelligence equipment; and

• training, maintenance, and sustainment.

(What's NOT on that list? Aircraft. What's the US doctrine way of winning a war, such as OIF? Air power.)