Thanks for the answer, but I probably put it wrong or incompletely.
I need a person to be able to enter their personal account not only on the website, but also in the Android/iOS application. All other functionality can be the same as it looks in the phone's browser.
Here's a related topic: https://stackoverflow.com/questions/31357370/how-to-frame-web-site-in-android-app and here how site looks like: http://1x-rate.com/
For example, you are a user - at the moment you need to go into the browser, enter site into the browser , go to the admin panel and only then the login process begins. I want a person to be able to download the application and click on it to get to the login page, and then everything happened identically to the browser.
We already tried to implement it this way https://stackoverflow.com/questions/31357370/how-to-frame-web-site-in-android-app, but as a result, the markup did not look correct, and the screen switching speed was very low.
I hope I made myself clear.
Does anyone have any ideas or experience creating a similar one?