I have been using the un-emulated agent for quite some time now and however using the emulated mobile agents has a huge margin on my mobile test results.
I tried to check the getTesters.php, however it seems like the agent is nowhere to be found there.
The physical iPhone is offline, unfortunately. Maintaining physical iOS devices at scale, and keeping them from dying, is tricky. 
For testing iOS, right now we strongly recommend using the iOS simulator at one of the M1 locations instead of emulation. Any emulation otherwise uses Chrome under the hood, which is going to give you very different results.
You’ll still see some differences—the CPU of the iPhone 8 is a bit slower than what the iOS simulator is going to do, but at least you get the real Safari under the hood so you can check browser differences, etc.
Thanks for your response @tkadlec .
Indeed, the test results from the iOS simulator might be a little different from the physical device, however that difference is just so minimal compared to the emulated version.