But according to an article in New World Notes, it seems work on the app has been postponed, possibly indefinately. Hamlet Au stated "A veteran Second Life insider" had send him a message, saying it was sent to him as one of the mobile app test group.
After reviewing the current state of the SL Mobile Viewer and the helpful feedback from residents, we have decided to pause development on this branch. The team is actively working on a new direction to take from here. We should have some news on that soon.
We’d like to thank you all for your time and feedback. It was very valuable to us! We will be closing TestFlight and the mobile regions on October 29th, 2021. Again, thank you for participation! Linden Lab
The source would also say of the development of the app, "It had been stagnant for months."
Hamlet messaged the Lab about the decision and is waiting for a response.
Stat tuned for more details
Hat Tip: Daniel Voyager