Is it feasible to create one's own in-app crypto wallet for a DeFi app instead of using 3rd party ones like MetaMask?

This is regarding the post i made yesterday; you can see my vision-statement for my project there in the comments there : https://www.reddit.com/r/ethereum/comments/152cjmy/can_we_use_smart_contracts_to_remove_the_need_for/?utm_source=share&utm_medium=web2x&context=3

Basically since the app is targetted towards a common layman who has probably never even bought a crypto token let alone have a wallet himself/herself; I want to have native wallet in my app to simplify things for the users. Plus, I am assuming they are not that tech-savvy too; therefore, i want to centralize all the services within the app and reduce the 3rd party services I use.

I just want to know if this is a good step; plus i'm still a newbie in the space, having dev experience of just 3 months so I'd have to educate myself on how to create a Crypto Wallet myself.

Any good resources would be welcomed; thnx