You should probably be more worried about losing your phone and someone accessing it (because you didn't lock it in time) than some zero-day exploit orchestrated by China.
In any case, you probably want to do something like this in approximately the following order (stop at the point where you feel safe):
TowoLabs is building that, you will have to check their page for announcement. https://nitter.net/TowoLabs
Or just monitor this place here, I'm sure someone will post it asap once available.
I don't understand what you mean with "set address". The ledger device will derive the flare address from your device seed, like all accounts. You cannot manually set or import a non-ledger address, that would defeat the purpose of the hardware wallet.