I've decided after the "human learning" revelation about these "smart" speakers that I won't be considering one. At best I'll be getting something that functions stand-alone without any internet access.
And here I thought that whoever is intelligent enough to transform Raspberry Pies into interesting stuff would have a mindset where inviting Amazon's 24/7 microphones into your home isn't a good idea. (Amazon, Google, Apple, Facebook, Huawei...)
A simple project has shown that the Raspberry Pi can, in conjunction with a Bluetooth speaker, become an Alexa-enabled device. There is no restriction on what type of Bluetooth speaker can be used, allowing a great deal of customisation with the project.