[janinge]

Yes, you wouldn't get this running on an existing smart speaker (without first rooting it and some serious hacking).

If you'r in the Apple ecosystem and are using AirPlay with your smart speaker(s), it's however possible to also play synchronized audio across to your own DIY speaker setup, using another open source project.

https://github.com/mikebrady/shairport-sync

Or you could of course choose to only use your old dumb speakers with this, and they will pop up as easily selectable sound output devices on all Apple devices connected to your network.

Or combine it (and librespot[2], owntone[3]...) with Snapcast to create a virtual speaker for your whole house that shows up everywhere.

[2] https://github.com/librespot-org/librespot

[3] https://github.com/owntone/owntone-server