[pndy]

Whatever we can say about how MS handled Windows Phone development, the OS itself was designed very well - my mother had no issues navigating and reading information out of it (on small HTC 8S), especially tiles. Now she struggles with Android Go on some cheap no-name device.

I still own Nokia 1320 which - if I'm not mistaken, was one of first "phablet" sized devices and I was quite fond of it up until applications have stopped working. Now it just works as any pre-smartphone device: I only pick up calls, send text messages; battery had to be replaced on 4th year which just confirmed the durability of electronics today and planned obsolescence. Back then I've managed to run some beta of Windows 10 Mobile but in the end, my Nokia didn't get it.

[rootsudo]

Sadly the easiest answer is just to get your Mom an iphone. Not the best but it will solve 99% of the issues and will last five years+ if you get a new model.

[skinnymuch]

Like other commentor said. Look for deals on iPhone SE 2020 or iPhone 12 mini or any other lowest iPhone mode since 2018 fall release (iPhone 11 and iPhone XR). Any of them will last for many years. Battery replacement might be needed after 3 years.