Can I enable ECC memory on an Intel NUC?

No, ECC is hardware locked on Intel NUCs. Intel’s 12th-gen consumer CPUs physically disable ECC at the silicon level, and the NUC platform doesn’t route the necessary signals for ECC UDIMMs. No BIOS hack or mod will enable it. For ECC, use an AsRock Rack or Supermicro board with Intel W-series or AMD Ryzen Pro/EPYC. Stick with non-ECC RAM for the NUC.