Amazon Echo, Google Home Hub, or whichever variant suits your budget and preferences
We bought a new HiFi unit late last year, then bought a Google Home Hub when they were on offer at £69 in December & promptly rendered the HiFi redundant.
The Hub is in our Kitchen so when I walk in to make breakfast I just say "Hey Google Play Jack FM"
From the conservatory I can ask it to turn the volume up or down
If I want something different "Hey Google play The Rolling Stones"
Previously it was either get up to turn on or adjust the HiFi or to find where I'd left the remote
Heading out and "Hey Google Stop" and it turns off
As well as music it provides various other options the Hub can access; Weather, my calendar, timer for my pizza
I expect a 7 year old would take to it like a duck to water