Not all mobile wallets have backup ,just because they are available for your smartphone doesnt mean they are reliable
Do not use mobile wallets with just username and passwords ,they are called online wallets ,they have no backup phrase or private keys.
For example I lost my bitcoin to xapo wallet since 2018 and they denied me of my coins after sending them mails.
Most probably your correct choose mobile wallet with have back keys to avoid losing of coins investment, I also using local mobile wallet herein my place where I resides two local wallet have choices both are have strong back keys but i choose the one very popular use by the people.