As a political scientist and linguist (not a scholar of ancient Buddhist texts) I feel compelled to chime in on this topic.
The English word “patriotism” (and its derivative “patriot”) has its origin in Latin and Greek root words for “father,” which themselves are derived from Indo-European root words such as the Sanskrit pitr, all of which are based on an onomatopoeic origination in the exclamation pa uttered by infants when recognizing a male parent. Thus, the modern-day notion of a patriot is someone who expresses kinship with individuals related through familial ties.
From a political point of view, patriotism is relatively new, at least in terms of the English usage of the word, and can be traced back only as far as the creation of territorially-defined political sovereignty as conceptualized in the West, i.e., the formation of the modern state system in the 16th and 17th centuries (the Oxford English Dictionary gives the first appearance of the word “patriot” in 1577).
Thus, from a political point of view, individuals during the Buddha’s time would not recognize the modern notion of patriotism, associated as it is with a system of states established in Europe and codified in 1648 at the end of the Thirty Years War with the Treaties of Westpahlia.
On the other hand, as illustrated by the association of Western idiomatic origination of the English “patriot” in Indo-European words meaning “father” (e.g., the Sanskrit pitr), clearly people during the Buddha’s times would be no stranger to associating political loyalty with familial relationships. That is, rule-making originates in the authority of family members and thus political systems founded on family and kinship ties produce a sense of loyalty bound to those ties. To the extent the Buddha had anything to say about what we today conceptualize as “patriotism” it would have to be put into this context.
On this question I defer to scholars of early Buddhist texts.