This is some gamble to make with unclear payoff. It costs billions of dollars to get the manufacturing contracts, hire the engineers, and obtain the procurement contracts. Not to mention the years of effort it would take. Unless you spend decades growing your own talent, the only way you're going to be able to attract the talent needed to build this project is by poaching them from Apple, Intel, Nvidia, and Huawei by doubling their salaries. And by buying out their non-compete agreements or hiring the best lawyers in the world. You're betting on two facts to remain true:

1. That the issue of avoiding American products will even be salient in three to four years' time. By that time it's pretty likely that America has either taken over the word or been reduced to rubble. Trump will either be god-emperor of mankind or leaving office a broken, defeated man (or perhaps in a coffin before that—the man eats more Mcdonald's than can be good for him, especially at his advanced age)
2. That people care enough about this to pay double the price of an American-made cell phone.
3. That your customers don't count the fact that their phones were made mostly by American or Chinese engineers against you. America attracted all the best tech talent in the world with high salaries and China basically brute forced it with sheer numbers.

Number 2 is really the problem here. Even if you could get a competitive cell phone to market literally tomorrow, it'd have to cost twice as much as an iPhone and four times the price of the latest Huawei or Xiaomi model. While customers are more than happy to pay $6 for Quebec maple syrup so they can avoid $3 Vermont syrup, the proposition of paying $3,000 for a Canadian cell phone versus $1,500 for an iPhone is a much more difficult one to accept. And one that not many people are likely to be able to afford.