You say you are using Ionic as a wrapper. You probably mean Capacitor? Are you just embedding your app from a public server in a Capacitor app, meaning loading all the assets from a public domain/server? Or are you building your app and shipping the assets in the native app (like a normal Capacitor app). Please explain a little more of what you are doing.
I wouldn’t recommend using cookies for auth. You can search these forums and you’ll find way more stories of issues than successes 
