Yeah NVidia usually fuses off their cores(Physically destroys the connections in silicon essentially), AMD usually do too but for low cost chips AMD often save money by just disabling them in the BIOS. Generally, if cores are disabled(Fused or not) it's because most of the silicon made for that SKU has non-functional cores and they didn't consider it worthwhile making a separate SKU for the dies with full functionality, so even then it's just pot luck whether an "unlock" would work.
Of course, NVidia has used the same TU106 die for the RTX2060, RTX2060S and RTX2070 now, the differences lie purely in what they fuse off[Though for the OG-2060 the fusing off of some of the memory bus also meant some PCB/memory changes], so from a market perspective they can't really leave the possibility open for unlocking.