Buying Smartphone and setting up Echo Dot for my easily confused 90-year-old Mom. Any suggestions?

My newly widowed Mom has a love/hate relationship with technology like computers and smartphones. She’s fascinated by what they can do, but is afraid she can’t learn to use them. In the first week or so after my Dad died in December 2020, (before any of us had been vaccinated) she was understandably scared and lonely. The only thing that cheered her was the prospect of getting and using the Echo Dot (Alexa) my husband and I bought her. She was under the impression that all you had to do was plug the Echo dot into the wall, and she’d be able to use it immediately. I explained to her that she (or more likely someone helping her) needed to connect it to another device (like a smartphone) before it would be usable, and since we were all in lockdown, we couldn’t visit until we were all vaccinated. Fast-forward to post-vaccination. I was scared and upset about walking into the independent-living apartment she and Dad shared in the last two years if his life. None of us had seen each other, even over Zoom, for a long time. Despite my having begged her to allow someone at the facility to set up and handle the technology for a Zoom call, she claimed that “wasn’t a priority,” so neither my son nor I had a chance to say goodbye to Dad. At least, I thought, despite everything that had and hadn’t happened during the worst of the pandemic, I could do one thing that might cheer her and make me feel useful: I could set up her Echo Dot with her phone or computer. Sadly, both devices were simply too old to be compatible with the Echo Dot technology. Mom doesn’t like the flip-phone she has, so I’d like to get her a new one anyway. She’s easily confused so I’d like to get a phone that is simple for her to use, but on which I can install the Amazon Alexa App. I have an IPhone myself, but I could just as well get her an Android or other brand. Any suggestions?