Good afternoon!
I have a question regarding the Android application.
If the application was deployed on one phone and I lost that phone, will I be able to install the application on another phone, reconnect to my data, and decrypt it again?
Yes you can, as long as your vault-data is not only on your device but anywhere online.
Just install the app on your new phone, connect it to your online storage, and add your vault.
If I use a NAS instead?
That’s ok as well. I just wanted to point out, that of course your vault is gone, if it’s only on the device, with no backup, and the device is stolen. Nothing particularly with Cryptomator. A simple „yes“ to your question would not have been sufficient from my point of view 
On the contrary Michael, I think you make a good point here, many MANY users I would imagine have just the ONE vault on their device, and when that is gone … for whatever reason, its gone.
Backup, wherever is a key point here folks, backup backup BACKUP 