If you’re not into the whole Google Home/Alexa/Apple Home echo system, and have Home Assistant already running, you could use them to build a bunch of smart assistants with Open Thread Border Routers.
I was just looking at doing this in my house but the cost of Pis vs used Google Gen2s with Thread Border Routers built in was cost prohibitive for me.
Do you have access to businesses upgrading computers or shutting down that division? They tend to have some interesting stuff for playing with on Linux.