I've swapped to using it since I switched to GrapheneOS. Only apps I've got using it so far are Tusky (Mastodon), Molly (Signal fork with UnifiedPush), and some of my self hosted stuff which allows for web hooks.
I really hope it catches on in more apps. Especially as their library has automatic fallback to Google's service.
I noticed this morning that mine is saying "No apps available" too. Not sure if the issue is withy Aurora or Google