AirPlay compatible routers?

Any router can handle AirPlay. It sounds like you may be asking if there are any other products that also include an audio output port, like the AirPort Express. Users typically connected a cable from the audio output port on AirPort Express to another amplifier or to a powered speaker.

An AppleTV will do this as well, but the audio output will be via HDMI, so your amplifier or powered speaker will need to have an HDMI input.

New, refurbished and used AirPort Express products are available on Ebay if you really do need another AirPort Express.

havent come across any

there are other airplay enabled devices though the appletv, homepod and a long list of third party devices

https://www.crutchfield.com/S-ysfK1pLJTI0/learn/what-works-with-airplay-2.html

https://www.the-ambient.com/guides/best-apple-airplay2-speakers-2020-2126

https://9to5mac.com/2019/01/08/airplay-2-tvs/

more

https://www.google.com/search?q=airplay+2+enabled+devices&oq=airplay+2+enabled+&aqs=chrome.4.69i57j0l6.6205j0j7&sourceid=chrome&ie=UTF-8