There are a lot of stuff US don't need or use they can send to Ukraine to deal with Russia, all those comes with minimal training required.
Bradley (US have around 250 stored somewhere not used and not in strategic reserve)
M109A6 (US have at least 450 stored and not used)
M60 Patton (US have 1000+ serviceable M60 in storage, waiting to be converted to target (Which mean it's going to be destroyed anyway) and already retired.)
M270 (US have around 200 M270 Marine retired when they fielded HIMARS.)
M113 (US have 4000+ M113 of all variants in storage, retired and waiting to be scraped)
M1128 Stryker MGS (US have retired the entire M1128 MGS just this year, there are 140 of those)
If US send all these to Ukriane, that is enough for the Ukrainian to mount an offensive. And that's just retired stuff, not stuff that we still use and can be spared, and that just US. I don't understand why US and EU are holding on to those old stock to begin with. The rationale is that you may need that for a conventional war with a near peer enemy, which is Russia, which is basically what these article being store in reserve is for, for them to fight Russia, then why not send them to Ukraine so they can do what they were stored to do??