Importing Samsung A73 into Canada

The big unknown is that there is never a 100% guarantee it'll work at all or at least work correctly. In theory if you're just looking at supported frequencies, the phone should work. A number of imported phones have issues with some features like VoLTE and wifi calling not working. Software updates can also be an issue depending on if the phone if from another carrier or if it's straight from Samsung. 

The 4G bands are going to very specifically depend in where you are in Canada. Telus uses a list of 4G bands. Some of the 4G frequencies are used primarily in rural settings (bands 12/13/17/29/71) and of those, the frequency found in any region can vary depending on what was installed and when. AWS is one of the primary band used in most areas (Bands 4+66 or 1.7/2.1 GHz). That's a combined pair of bands used together. Some urban areas are using bands 2+25 (combined) also which wouldn't work with the A73 since it lacks band 25.

5G is going to really depend on where you are. The original 5G uses band n66, which is the most common. Telus has  also recently been deploying a second higher frequency 5G technology, which the A73 does not support, band n78 or 3.5GHz.