There's a lot of moving parts going on here, and I suspect that there is an option that can be found that simplifies things for you across the board given a few more details on usage expectations.
In the mean time, however, let me present you with a mobile data provider worth looking into -
Mellenicom. They're basically a T-Mo business wholesaler, and they offer international data roaming. Give them a call and explain what you're needing to do. Might be a good fit.
KnowRoaming might also be worth giving a gander and being aware of, as well as
OneSimCard and
WorldSIM. They may provide you with some
potential options that could roll up both your US and Canadian mobile and data services all in one package, or at least add on international roaming options to a domestic MVNO of your choice. It's also worth noting that incoming texts and sometimes talk minutes with these carriers are free, so factor that in your price calculations. Don't know for certain without greater details.
Regarding GoogleFi, alternatives to Tracfone, hardware costs, etc. One thing to do is not be so short sighted that you don't calculate lifetime costs with alternatives. Equipment, monthly fees, all of it should be priced out over the next X years you'll be needing to do this with all your potential solutions.
Not much, but it's a start, and a few more options to consider.
