Is it at all possible to find a way to connect the LCD screen from an Iphone/Android to a PC via HDMI using connectors etc?
Yes, no, maybe...
You can find various and specialized 'LCD driver boards' that will run generic LCD screens, or specific screens from apple, samsung, sony, etc.
Step 1 is to identify the LCD. (Model and Manufacturer, or the signalling type)
Step 2 is to google search for an "LCD driver board", or "HDMI to (Insert signal type here)"
Step 3 is to plug them in.
I've seen lots of MIPI DSI boards and projects kicking around. If you are lucky, you have something that can be used as a standard device... otherwise it may be time to google around to buy a small LCD with an included driver board.
(They are readily available from many sources)