I live for a lot of the time in France and would like to use the Alexa/Google assistant functions, in English language, on a Bose Home 300 which I bought in the UK. I have a UK Amazon account and obviously French wifi.
Welcome to the community, thank you for reaching out.
This should be possible to alter the language through your Alexa app. If you visit the application and go to Setting --> Device Settings --> Device Name --> Language this will allow you to set your products chosen Alexa language.
I hope this helps, do let us know if you have any further questions.