Will a unlocked Bell iPhone 5 work with a Fido SIM?

If I get an iPhone 5 from Bell and unlock it, then put a nano LTE SIM from Fido, would that work?

Yes it will, you might have to get the SIM card trimmed a little bit depending on which type of SIM card you are dealing with. But other than that, yes if it is unlocked, you may.

Of-course it will 100% work.