To anyone still struggling with this, I found a cleaner (if tedious) setup. It does involve using Samsung routines. First, set up your "Extend Unlock" how you want, like if you're at home or simply connected to your PC.
On your phone, go to the Galaxy Store and download "Good Lock"
In "Good Lock," go to "Life Up" and download "Routines +"
Go to the Play Store and download an app called "NTFY"
Open "NTFY" and subscribe to a Topic. Essentially, this is just your own custom server name.
Set up a routine. I called mine "Unlock Device"
Add an "If" condition for Notification Received with a specific keyword. Set the keyword and specify that it's coming from the "NTFY" app
Add the following "Then" statements: 1 - Functions>Navigation button action>Home>Done; 2 - Advanced options>Wait before next action>1 second>Done; 3 - Good Lock>Touch macro>Add>OneUI Home>Create a macro where you swipe the screen>Done
Save your routine
On your PC, open your notepad app and copy this line: curl -d "Device Unlocked" ntfy.sh/"NTFY Topic"
"NTFY Topic" is the name of the server you made in the NTFY app on your phone
Save this as a .bat file
At this point, you can be done! Anytime you need to unlock your phone to use it from Phone Link, you can click on this .bat file to unlock your phone to the home screen before mirroring. You can also get a little more fancy like I did and download Bat to Exe converter to turn it into an executable that can be pinned to the Start menu and activated with 1 click.