This interestingly aligns well with the hypothesis that the Cimmerians were not (at least not initially) Iranic speakers, but speakers of something Daco-Thracian or closely related to it, ultimately descending from a language of the Catacomb culture, but perhaps ruled by an originally foreign Iranic-speaking elite (a first signal of Scythian expansion before other Scythians drove them away altogether, forcing them to move to Caucasia, Anatolia and the Balkans, while absorbing those who stayed?).
The western Scythians seem to have been considerably different from the eastern Scythians right from the start, even before the East Asian-shifting population movements from the later half of 1st millennium B.C. onwards (especially from the times of the Xiongnu Empire), a fact that could indicate that much of the local Scythians, in the western steppes and adjacent areas in Romania, Hungary etc., were assimilated Daco-Thracians from the steppe and also different ones from the forested areas.
Such an origin for Daco-Thracian could help explain the noted similarities with Balto-Slavic, that is, it's pretty plausible if Daco-Thracian was originally spoken in the Ukrainian steppe and forest-steppe just south of where Balto-Slavic was evolving in northern Ukraine, Belarus, Poland and westernmost Russia.
Just some loud ramblings and speculations of mine... LOL
There was a steppe culture involved in the formation of G?va, but rather as a fringe phenomenon and in the end the Channelled Ware people rather pushed it back. But the debate was and still is ongoing. Its the Noua culture which was part of the great west and southward movements of steppe people, some related to the chariot complex, which might have contributed to the collapse of Unetice and helped the spread of Proto-Greek.
In Transylvania they pushed Wietenberg back and controlled large areas. But G?va while complex in origin and absorbing some of these pastoralist steppe elements, seems to rather have pushed them back. But then again, there are numerous Northern, Western, Southern and Eastern influences, all working on the Tisza basin population which seems to be crucial, which could all contributed the lineage. But going by the E-V13 phylogeny, its also about the latest time for the start of the massive expansion, because it started slower in the Middle branch age, with the basic branches being formed, then these branches experienced in the LBA-EIA massive founder effects. Kind of preparing the stage for their greatest moment. So they had to be in an at least stable growing, relatively successful population from the Middle Bronze Age on.
This just fits the best with some pre-G?va context everything considered.
As for Liguria, I'm very tempted to attribute most of the variation we could observe in Sardinians from Cagliari to Northern Italians, especially Genuese. I also see that in the STR results of some, but I'm no expert on interpreting these and they are not always reliable anyway for lesser known subclades. If the Cagliari samples represent largely the Ligurian/North Italian rather than Southern influence, which I know is debatable, but possible, also because of accompanying other more Northern lineages, this would speak for a Northern land route and a fairly high diversity from the LBA. It would also allign well with the Italian study which noted Northern clusters and a good age in Italy. Their estimate fit the best with a LBA-EIA expansion, but that's not safe of course, just a good model they proposed. But that they came to a LBA date is quite a coincidence if its not true.