only a handful of investigators at most have been assigned to work on the Nord Stream case on a full-time basis.
the perception among investigators is that the will to solve the case is not particularly pronounced in the capital. Politically, it is easier to live with what happened if it remains unclear who is behind the attacks.
A case could probably be made for either side. Russia supposedly has done this before in Georgia
Sure, but it seems not even the US/NATO is claiming it was the Russians at this point. Actually, I'm not certain if they ever did so in the first place? I honestly don't remember.
https://www.forbes.com/sites/tylerroush/2023/03/07/us-thinks-pro-ukrainian-group-blew-up-nord-stream-pipelines-report-says/