Homey Pro says ”App unavailable” for Aqara

No idea waht you mean. It is available is the store. Is installing and working here.

Also there is a topic specific for questions about the app here: [APP] Aqara & Xiaomi Smart Home - A different kind of Smart Home solution (Zigbee App)

But if you are not clear in the issues you see you probably first need to be more specific

[Tip] Problems with Homey?