Here is the situation. There is a mobile site I use a lot. It's very useful. But it only works on mobile. My phone screen is a few inches across. My desktop computer has three large monitors and several square feet of viewing space. SO of course I'd rather use the site there. But simply tying the mobile url into my browser isn't enough. m.example.com still won't show the real mobile site unless I ALSO change my browser's user agent to be that of an iPhone.
So you CAN do that in the dev tools. I can open a new window, change the user agent, go to the mobile URL and I will get the 'real' mobile version of the site and it will work totally normally.
What I'm trying to do is simpllify that process. I made my own "wrapper" page that itself contains not much more than an iframe. It loads the mobile site. But this will only work if there's some way I can change the user agent of the frame. I've found a few references to a method here on stackoverflow but it doesn't seem to work. I'm trying on firefox and safari.
Is there any way to do this, or is it all old stuff that's now blocked by the browser? As a web dev, I could see how this could also be a useful tool for doing mobile web dev without having to actually grab my box of old smart phones and fire them all up.