I know the title is a bit off, but what I'm asking is if it is possible to have a python script on my website that can detect if my Android phone is connected to the computer Im using to view the page. I don't know if this is possible since I think python is server-side, but maybe this is possible to do with JavaScript? I'm fairly new to programming so I may not be as smart as you guys out there but if someone could just lead me in the right direction I would be grateful.
What you're looking for isn't possible and should not be possible for security concerns.  Do you want someone knowing what devices you have connected to your computer?  You're essentially wanting a device sniffer but a website would not be capable of accessing the client's machine in this manner to access the desired information.
Python on website to connect to phone connected to computer