I use three Airport Express base stations each hooked up to class-D amp/speakers so we can have music around the house. And this past week Apple—surprisingly—released a firmware update for these discontinued devices that gives them support for AirPlay 2. AirPlay 2 eliminates any audio latency between devices that may be playing simultaneiously (such as a pair of HomePods used in stereo). While this wasn't much of a problem at my house before the update—minimal latency was detectable occasionally and wasn't too distracting—I can attest that there is zero detectable latency now.
The Airport Express is a great option for creating an AirPlay audio network and you can still find them being sold as refurbs, used on eBay and elsewhere. They aren't exactly using modern WiFi or security protocols, but if this isn't an issue at your house it may be an inexpensive way to wirelessly extend your audio system.
The "Kitchen Express" on top of our refrigerator.