I'm not downplaying your achievement, it's incredible that you've done everything that you have including getting the grant.
The only caveat being that you didn't have a network. I think that's what doing a masters programme is for... developing a network, that will lead you to an advisor and hence a "formal" PhD programme.
I don't have a PhD, but I would love to go back to school and get one. Been rejected 4 times now so I guess my time is running out or already has.
I love that options like this exist, in your searches have you found something for Canadian citizens/PR holders (I'm not a US citizen so this method won't work)?
The only Fellowship I know of that funds US grad school applicants but also allows PR would be the Hertz Fellowship[1]. It permits "gap year" students, so depends whether that applies to you. I think Hertz is significantly more competitive than GRFP.
[1] https://www.hertzfoundation.org/the-fellowship/eligibility-b...