Turn your old phone into a hardware wallet with a tap.
Cupcake: Security, Made Easy — description
Cupcake makes it easy for anyone to secure their crypto by turning any old phone into a powerful air-gapped hardware wallet, with Bitcoin and Monero support out of the box. Easily pair Cupcake with Cake Wallet to get the best of both worlds, combining the ultimate security of Cupcake with powerful exchange functionality, hot wallet support, and much more.
Note: as Cupcake is a companion app for air-gapped signing, for full functionality, you'll need to pair Cupcake with Cake Wallet or Monero.com wallet on an internet-connected device!