There are some interesting strategic implications here if Nordstream2 is halted or the US ups the sanctions. Either would be the result of US actions aimed at hurting Russia..
In neither case would the US suffer any economic hit as the current trade between US/Russia is unlikely to be affected as it hasn't been to date.
Well there is the other case where Russia might realise the US is never going to stop and that real return actions need to be made... perhaps drastic stuff, like no more rocket motors for a country that competes with us (compensated by using more of them ourselves of course), or even a nice big tariff on titanium sales to the US, and perhaps even a large tariff on LNG sales to the US as well so they don't feel Russia is trying to control them with cheap gas supplies. Tariffs on raw materials exports to encourage local use and value added export sales. The money could be invested in all sorts of things that could be useful...
I think letting Germany break the deal with NSII is the best option and when they do redesign the pipeline to deliver gas directly to Kaliningrad... add power cables and data connections to the pipe to make it a more useful connection to a part of Russia that can no longer be reached reliably by land.
Replacing critical US products and technologies so they can not only be independent of the US but also be able to then sell to the rest of the world in direct competition to the US as well.
Ultimately Europe paying more for energy is good for Russia... embrace it... the US doesn't have enough gas for domestic use let alone enough to support Europe.
Regarding the subject of the thread, if the Germans cannot give the so called evidence they have to Russia then Russia has nothing to investigate... pretty damn simple. And the same applies to the Skripals too, if the British refuse to hand over evidence then there is nothing to explain or investigate... it is clearly just political bullshit.
Any sanctions imposed by the EU regarding this so called incident should be replied to magnified because without evidence their sanctions are unfounded, whereas responding Russian sanctions will be based justifiably on sanctions imposed on them without and justification.
I am sure Russia has a list of things they can always hit back with, so this time choose multiple entries for each sanction because it makes sense to do so.... and keep up that list because no doubt you are going to need it quite a bit this year for helping Trump get reelected, and when it is proven that Russia created Covid 19 because their Vaccine is the only one that works and for no other reason they are prepared to talk about in public...