The US can do whatever the fuck it wants with the vaccine it produces domestically. Trump's decision to prioritize vaccine distribution for Americans was an executive order, and Biden could rescind that with a flick of his wrist. Besides which, it's not a donation when Canada's signed contracts to purchase vaccine. (and even if it was, Biden could "renegotiate" those contracts in a heartbeat, if he wanted to)
As of February 2nd, of the currently approved vaccines, Canada purchased:
20 million Moderna vaccines on July 24th, 2020, and optioned another 20 million in early December
20 million Pfizer vaccines on August 1st, 2020, and optioned another 20 million in early 2021
10 million Johnson & Johnson vaccines on August 24th, with options for another 28 million
20 million AstraZeneca vaccines on September 24th
Of the vaccines awaiting approval, Canada purchased:
52 million Novavax vaccines on August 27th, with options for another 20 million
52 million Sanofi vaccines, with options for another 20 million
20 million Medicago vaccines, with options for another 56 million
Our problem is not that we were slow to secure vaccine contracts (we were consistently one of the first countries in the world to secure vaccine contracts, sometimes *the* first), or that we didn't secure enough (we've got contracts for 400% more vaccine than our population needs), or that our supply chain has failed to get needles into arms (we are, and in any case healthcare is provincially administered, not federally)
The problem is countries capable of producing vaccine, like the US, are hoarding it for themselves before anyone else.
(and Canada's loss of domestic vaccine production happened under Mulroney's administration back in 1980, so blame for that falls on every administration since then. The Trudeau administration is investing ~$170 million in upgrading the NRC facility to give us domestic production capacity)