How to serve a file for mobile

I have an index.html page that has an autoplay YouTube video background. Since iOS won’t allow that to display on a phone/ipad I want to be able to serve an m.index.html version for mobile that has a poster displayed instead of the autoplay version.

Can anyone offer some insight how to accomplish this? Must I get into browser sniffing and redirects and so forth? Some way to use Wappler’s display properties > hide on?

To be clear, I don’t want to develop a mobile app. I just want to serve a different page for a request from a mobile device.

the age with YouTube video background