I don't know a lot about IOS, but in Android you can create shortcuts of website pages in your homescreen and it might work.
About what you are asking, you can both use some cross-platform tool, like Cordova. (I posted the most famous, I'm not here to explain which cross-platform tool is the best one, there are enough questions for this). Btw with Cordova you can build your own application using html, css, js.
Now, if you want something native, simply check a tutorial on how to create a webapplication(android official guide).
It's pretty simple and doesn't require that much skill.
Note#1: I think I have to tell you an economic note: publishing is not free, for example IOS
costs around 100$/year. So consider if you really want do build an app only displaying a website. It's a more common and (imho) a best way of doing things, building a complete application with all buy, ... tools. Usually people dislike webapp if they can see the exact same thing with the mobile browser.
Usually apps gives something more than a simple website.
Note#2: I don't know if Apple allows you to build an app showing only a website, you should inform
Note#3: you should move your question, this community is for code, if you want some hint look for google or other platforms, there are a lot of "how to" on the net :)