Take a look at the home assistant voice preview device.

It has a 3.5mm jack out to connect to better speakers. You should be able to integrate some aspect of audio playback.

From the FAQ

Can I play music on this device?

Yes, if you plug an external speaker into the 3.5mm audio port. The built-in speaker is meant for voice feedback and is not optimized for listening to music, but the included DAC is capable of playing lossless audio on a suitable external speaker. We recommend using Music Assistant to control music playback.

Good to know, thanks!

I’m not sure about self hosted specific. There is a device called WiiM. Works with most of the major streaming services. I believe they’re also working on plexamp integration too.