There are cellphones made for seniors, i.e. simple to use, large keys, hearing aid compatible, etc. Perhaps the largest provider is Jitterbug in the US. I have no idea if their phones are GSM let alone unlocked. (I suspect not because they make money from phone plans.)
Some suggestions:
1. Call Rogers and ask them what phones they offer for disabled customers. They probably don't have anything specifically designed for them but they may be able to suggest a regular phone that has particularly large keys, etc. Although Rogers phones are locked they will work on the SpeakOut network. Of course you would then need to by a SO SIM along with the phone. Or you may want to consider a Rogers or Fido PAYG plan.
2. There is a GSM phone designed for seniors that's available in Europe, EmporiaLife. Note that the article says it comes in a 850/1900MHz model (that would work in Canada.) The manufacturer is in Austria but I found one dealer in the UK. The phone isn't cheap at £125 (~CA$250.)
3. You may want to Google around for "cellphones for seniors" or "cellphones for disabled" etc. to see if there's anything else out there.
4. If you are prepared to consider a non-SO solution then contact Bell and Telus to ask what they have to offer.