Windows Upgrade Help and more

This. Agreed, and if it's still stuck, a quick call to Microsoft support usually gets it sorted fast—they can push the activation through on their end.

This. You could also check if there's a critical BIOS update from Dell specifically for TPM 2.0 readiness. Another option is to just do a clean install from a USB drive, which sometimes bypasses the upgrade checker.

This. You could also check if TPM 2.0 is enabled in your BIOS, as that's a common blocker even with a supported CPU.