I, too, am very interested in an APK. I would love to subscribe to Windy if an APK were offered. As a pilot, I can say it would be amazing. I refuse to clutter my phone with google play. There are over 4 million users on Lineage alone in the world, 200k in the US.
At the very least I am curious for a legitimate reason why it would not be offered.
P.S. Fdroid is an option as well.