Windows 10 through external hard drive / Boot Camp issues

Hello.

So I recently purchased an external hard drive (Seagate 2TB Slim BUP) in hopes of running Windows 10 on it just because I didn't want to partition my internal drive on my 2019 iMac. I made sure it was possible and used this video to figure out how to do it. After a bit of trial and error I successfully managed to install Windows 10 onto the external drive utilizing Parallels and I have been able to boot into the drive and onto Windows 10 using the option key command at startup. I got so far as starting the setup from Windows Support -> Boot Camp -> Setup where it was supposed to install all of the appropriate drivers to allow connection with the Apple Keyboard and Apple Mouse as well being able to set up the WiFi in Windows.

However, even after allowing the Setup to run and install all it needed to and then restarting my computer, I log back onto Windows only to find out that I can't use the Apple Keyboard, Mouse or wireless internet still, and I'm not sure why. I've looked up a lot of tutorials and forums online and I've tried uninstalling/removing drivers from the Device Manager in Windows but any time I try to update the drivers with the yellow exclamation point on it (the drop down list for "Other Devices"), the notification pops up saying it could not find the appropriate driver for it. And even in trying to change/add a wireless driver from a set list (i.e. Broadcom drivers), the wireless internet functionality still does not show up on the system. I saw one video where they said to update the drivers from the Boot Camp folder in the Windows Support, but there were no drivers for wireless internet in them, only for BroadcomEthernet and BroadcomBluetooth while they had BroadcomWireless in theirs. And I can't download anything from the internet onto the Windows system because it won't connect so I'm just at a loss and I'm not sure what to do.

Any advice is very much appreciated!