As we now know, it wasn't just F-16s. Time and again, the Biden admin (I blame Jake Sullivan) was worried about crossing Moscow's red lines and thus sparking a regional war that could draw in NATO via Article 5.* Like the deteriorating situation in Afghanistan in the spring of 2021, everything was slowly reactive compared to real-time needs. Turns out all those red lines weren't actual red lines; and while Ukraine has defended itself admirably, it never had any real chance of outright winning the war. Being handcuffed along the way didn't help.We could have shaved some time off (months at least) by starting language and technical training earlier than we did. Also by allowing contractors to work inside Ukraine sooner to help maintain their new fleet until they get more experience.
Even if Trump wasn't a shill, I don't know how any negotiated deal doesn't result in recognizing de facto territorial losses in some form. If UA was forced to cede Crimea and Crimea only, would they accept? I don't think they would, but I think that is a minimum ask for Russia.
* To be fair, the rationale itself isn't wrong.