Hello Zwatson,
Happy New Year and Welcome to the Community!
Sorry to hear of your situation. I understand you live in a major city (ie Calgary), however, extended coverage (Fido-EXT) isn't limited to rural areas. The only criteria is that you device is unable to access Fido/Rogers coverage, but within another provider's coverage. The roaming agreements allow a different mobile provider's customers to temporarily use their networks as a courtesy. I have recounted this story before but it illustrates the point. We regularly visit Port Elgin, ON (admittedly, not as big as Calgary). Where we stay, on one side of the main street, we connect to Fido. However, on the other side of the street our devices connect to Fido-EXT. It's only a couple of metres, but it's enough to for Fido/Rogers coverage to be unreachable on our devices on that side of the street.
I understand your spare phone is able to access the Fido/Rogers network so it's likely there are those cellular towers in the area. You can get an idea of your area cellular towers here. However, in addition to your proximity to the cellular towers, there are many factors can affect cellular reception (see here and here). It's possible your spare phone has better cellular reception than your new phone. If that is the case, that could explain why your new phone is unable to receive Fido/Rogers signal when you attempted to manually connect.
I also understand that your phone appears to have a good antenna (see here). However, others have also noted cellular reception issues with that device (see here, here, and here, etc).
I also understand you have attempted to change the APN settings. You might consider verifying the settings you used were the same as listed here.
It's also possible your spare phone is connecting to a different Fido/Rogers network than your new phone (ie '3G' vs LTE or 5G). You might consider disabling 5G to see if your new phone is able to connect to the Fido/Rogers LTE or '3G' networks. You might also consider disabling LTE as well to see if your phone is able to connect to their '3G' network.
Was your phone purchased from Fido? If not, is it a Canadian version of the device? If it is not a Canadian version, have you verified it has compatible bands/frequencies? You can verify the compatible bands/frequencies here. If supported, have you attempted to use Wifi-calling with the phone?
If the issue is with your new phone, you might be able to get a burner and use your Fido SIM card (similar to your spare phone). Unfortunately, if your circumstances don't allow for adequate cellular signal on your new phone, there isn't much that can be done. It's a common misunderstanding that any mobile provider will suit everyone everywhere. That simply isn't the case. If you spend a good portion of time outside of a mobile provider's coverage or your phone is unable to receive signal at your location, perhaps that mobile provider isn't the right one for you.
Hope this helps 😀
Cheers
