It is an interesting question, Rosa. I know I have read about families buying them for their dementia-suffering parents, and having some success, but I can't remember where. I did find this:
https://www.caringseniorservice.com/...helps-dementia
that gives some ideas of how it could be used. It would not have worked for my parents because he can't hear well enough, and her dementia was way too far gone to use it. I think it depend on your mom's hearing and where she is in the process? Maybe if you get it early enough, and then she could adapt to it and stay adapted?
Mom used her computer for years with dementia and then suddenly could not do it anymore. It was kind of a sudden thing, and I think it is happening to my dad now, that he can't get back on track with the device because you know how these machines will do something, a screen won't open, or something will pop up--they both have lost the ability to deal with that kind of mechanical thing that happens, so she can't make phone calls anymore, for example, and I'm not sure about him; I always call and he never does, so it's pretty much a stretch for him to dial a number.
Those are just examples of human/mechanical interface. But I know some families have found a lot of success with Alexa so maybe give it a try?