Based on y chromosomes, the Germans have a haplogroup L1 all to themselves and their kin. This should be the main contributor to the substratum in their language. Uralic and Finno-Ugric people likely originate from N haplogroup, although they are very mixed now. So it's unlikely the substratum language in Germanic is Uralic. The R1b haplogroup in Germans likely originate from the Bell Beaker people who might be related to the Basques, so it might be worth also to find traces of Vasconic as well in German. Despite the baseless assertions of Aryanists, R1b is clearly not part of the Indo-European invasion.