Worked like this for you?

After a little research I think it should work like this:

- when you set up Phoenix you get a 12 Word seed

- with your first TX Phoenix will open a LN Channel to their ACINQ Node

- so your Smartphone becomes a LN Node

- if you or Phoenix close the channel you can for example use the BlueWallet onchain Wallet to see your funds onchain again (use your seed)

- while using Phoenix you should run the App from time to time (every day a short time is recommended I've read, but longer periods should work too)

I didn't try it by myself yet.

But the theory/research said it should work this way.