Make changes in metamask-mobile, a react native application so that It works with a custom RPC.
Knowledge of [login to view URL] is an advantage but you can read the documentation of [login to view URL] if you are not familiar with web3.
Please search the metamask-mobile repository on github. You have to make changes to this app. you can download the metamask app from playstore as well.
The app needs to be rebranded and some other changes are required.
Though it is a blockchain based app, mostly, it is just about calling external api's and showing the data.
To know more about this project, just send me a message.