While you are correct that a number of these "tribes" settled in regions where modern nation-states were founded, to connect these post-Roman political entities to the modern ones is taking this reading perhaps a bit too far and falling down the rabbit hole of the nineteenth century origins of "modern" medieval studies.

Case in point, the Franks were divided into multiple groups all ruled by petty kings. They were eventually united by Clovis I, more or less, who was the ruler of the Salian Franks, a group living in what is now the Netherlands and Belgium. The language the spoke was closer to Dutch, and they imposed their own LOOSE hegemony over a region that partially covers what is now modern day France. Their Mayors of the Palace, the Pippinids, who would eventually overthrow the Merovingians and establish what would become the Carolingian dynasty had their capital in modern Germany. BOTH modern French and German nationalisms looked to Charlemagne and his Salian dynasty as their progenitors. This info can be found in a wide variety of books, but I personally slogged through the New Cambridge Medieval History vols. 1 and 2 while catching myself in up in grad school.

I'm not going go down each of these one by one and deconstruct why connecting these Germanic forebears to the modern nation state pushes too hard, but I would be remiss to omit the Lombards given that I did my dissertation on medieval Italy and spent quite a bit of time pondering the disillusion of the Lombard Kingdom extensively.

First, the Lombards were not the first or the last Germanic group to settle the Italian peninsula. The Goths established a hard-fought and short-lived kingdom in the peninsula when the Lombards invaded. It is important to note that the legal structure of the Lombard kingdom, that is to say a king sitting at Pavia ruling through the authority of some sort of legal experts. This sort of structure remained in place through the Carolingian period, and this structure became the theoretical basis for particularly northern Italian legal systems. There's an absolutely wonderful book on the subject by Charles Radding called The Origins of Medieval Jurisprudence: Pavia and Bologna. That said, to say that this is the origins of "Italy" would be a mistake. Throughout the Middle Ages, in northern Italy, the Holy Roman Emperor remained a theoretical source of legal authority in Northern Italy. This connectedness led to many early Italian nationalists to believing that the new nation state should only be comprised of the north. Indeed, if one were forced to draw a line between the Lombard/Carolingian kingdoms of Italy and modernity, you would find that that line ends in the kingdom of Austria, which had to be driven out by the Italians, led by the French-speaking aristocracy of Piedmont. Italy is perhaps an extreme variety. One can certainly find the seeds of modern England in the Anglo-Saxon era of you squint, but Switzerland's origins are thoroughly modern.

Does this make sense?