If you have a Tech2 you can probably unlock a Delco radio by doing a theft lock relearn.
I'd get your four digit theft code and put it on a business card in your owner manual or just write the four numbers on the inside of the back cover with no explanation after you mate it using your Tech2.
This came from here --->
https://www.obd2tool.com/blog/2021/0...an-auto-radio/
Connect Tech2 to the OBD port of the vehicle. When the screen of the tool illuminates, it means the tool is connected to the car. Then you can start the process:
1. Go to the main menu and select: Diagnostics.
2. Select Vehicle Identification and then run through the following options:
– Model Year
– LD Trk, MPV, Incomplete
3. At the System Selection Menu screen, select: Body
4. At the Vehicle Identification screen, select the following:
– Appropriate model
– Appropriate Air Conditioning
– Navigation Radio
5. Select: Navigation Radio.
6. Select: Special Functions.
7. Select: VIN Relearn.
8. Then you will get a message: “Do you want to clear radio theft information?”
9. To begin clearing, press the soft touch key on the top right of the scan tool. The scan tool will display “Clearing Radio Theft in Progress.”
10. Press EXIT on the scan tool and cycle the ignition.
Disconnect the Tech2 scanner from the car when finished.