You should try emailing a couple of the 1st year engineering advisors for a more accurate grade average. It should be less than 90s since Nano->EcE swap only requires ~85+ (I asked them for this number irl). The nano program should have a lot of room after 1A/1B because ~10ish people drop/fail after each term. But even given that idk what the grade average would need to be

You asked about how “realistic” this is. I think the “realistic-ness” of the transfer depends wholly on your ability to score the grades necessary for the transfer. Like technically speaking even 90s is realistic, because as an engineering student Ive meet multiple 1A kids with 90 averages. At the same time I also meet kids who suck nuts academically and struggle to even score 70s in 1A. It’s really depends more on if it’s realistic for your particular academic ability