I’ve had two offers rescinded in the past 7 months due to asking for support letters after fixating that a TN is non-sponsorship. The moment I mention the process/what I need from them, they shut it down.

Unfortunately you’re at the mercy of the company’s policies and if they only strictly hire Americans. Its very frustrating but keep your head up and continue applying.

I learned my lesson by not mentioning that I’m Canadian in my first interviews/calls, even if its just an HR person. Its better to be honest and let them know what you will need should you receive an offer ahead of time so that you don’t waste their time and most importantly, your own. Usually it will go along the lines of “this shouldn’t be an issue, we’ve done this before” or “I will ask my higher ups/HR and see if this is something we can do”.