My issue with that is how many countries in NATO actually have modern, working MBTs in any significant number? The focus for a while was putting pressure on Germany to approve the export of Leopard 2 tanks to Ukraine because there were supposedly plenty of them available in Europe. In reality, it seems what was available on paper and what's actually usable is very different. For example, most of Spain's L2s are apparently broken. It's so bad that countries are looking to give L1s instead.We wouldn't have to. If it actually gets to a point where we're going into a war that requires a massed deployment of armour then there's a overwhelming chance that NATO will be involved. NATO tanks will pick up the slack.
The USA has plenty of very good MBTs but they aren't a reliable NATO ally. If Trump or a similar right wing Republican gets back into power, they might even withdraw from NATO.
That said, if it were up to me, I'd give Ukraine most of our Challenger 2s anyway, and start the process of buying new tanks to replace them. We could even loan them the C2s under the condition they give any working ones back after the war.