Not a lawyer, but isn't that kind of dicey? The TN is non-immigration and temporary - it's not supposed to be used if you have any intention of permanently migrating. I'd worry about it putting your TN status in jeopardy.
True but that doesn't really impact your ability to apply for a Green Card from TN. You have to wait 91 days [0] since your last entry before making an adjustment of status application.
Every year thousands of people in statuses like F-1, O-1 and TN get employment based green cards. The idea that you have to be in H-1B or L-1 status to get an employment GC is simply 100% false.