I work on heavy equipment with mostly cummins and cat engines. About 10 years ago caterpillar did a bunch of testing on ultra low sulfur fuel. Their results were the ulsf has no effect on the wear on their fuel systems and it was ok to use on all cat diesels
To the OP: If your engine has a DPF then do not add 2-stroke oil as it will foul it up.
ULSD (Both Euro and US) is additized with lubricity enhancers to make up for the lubricity components which were removed along with the sulphur. Currently the max wear scar rating on US ULSD is 520um and Euro ULSD is ~460um(IIRC). Lower is better.
Diesel common rail manufacturers add coatings to the internals of their HPFP pumps when they're going to be fitted to vehicles which use diesel that has a little lower lubricity. US for example.
As for additives there is a plethora of products out there, but IMO nothing works better than biodiesel @ 2% (B2) for lubricity. It's just enough to be more than adequate and not so much that it'll cause problems if it's not up to par in terms of quality.
The reality is that the majority of diesel fuel sold in the US is well within spec and even close to Euro spec when it comes to lubricity. Now it's clear that the newer VW TDi's with their Bosch 4.0 common rail system have been having problems but from what I've read the issue is mis-fueling (gas) and/or the decision to use aluminium instead of steel for housing of the HPFP.