No commercial Blu-ray exists. Any BDMV of S02 is either:

Zero. No behind-the-scenes, no commentaries.

If you’re a collector seeking the highest quality for Shetland S02, the official DVD is the only legitimate option. The BDMV versions floating on private trackers offer slightly sharper upscaled video but are technically non-compliant and lack Blu-ray’s usual advantages. Only recommended for Shetland completists who enjoy tinkering with media servers and don’t mind ethical gray areas.