p.s. I mean writing the source code to create a platform that then other people can also create your own wallet.
You must consider a lot of things first since there is many wallet who came first for now and surely many people prefer to used that since that wallets are tried and tested,
But if you pursue this project well you must need to have a lot of money to market it so it would reach to crypto people and might gonna used it, and also you must do some other background and feedback checking for the past wallets, and who is successfull and who is not since you can get more pointers from them on how you would run your business.