Hoppe's whole speech is good, in my opinion, but here's another excerpt that gives a flavor of what Haller was describing:
"A prince’s direct rule extends only to his own property, just as in the case of every other person and his property, and as we will see shortly, it is only in regard to this “self-administration” of one’s own property that there exists somewhat of a difference between a prince and everyone else. In any case, as a private law subject, a prince does not rule over other people and their property, however, (p. 479)  – except insofar as these have voluntarily attached themselves to the prince and entered into some sort of social relationship with him to better satisfy this need or that. Hence, in distinct contrast to the modern state, a prince may not unilaterally pass legislative decrees or impose taxes on other people and their property (p. 450, Fn. 8). Rather, whatever dependencies or servitudes there may exist vis-à -vis a prince they vary from one dependent to another, and in any case they are all voluntarily accepted and may be dissolved once they are no longer deemed mutually beneficial. – And Haller adds some illuminating terminological observations to further clarify this status of a prince as a mere private law subject (see p. 480, Fn. 14): The most appropriate way to refer to the status of a prince, king, etc., then, is to identify him simply as the head of a particular household, such as the head of the house of Bourbon, or the house of Habsburg, Hohenzollern or Wittelsbach, etc., for instance. Less appropriate, and already slightly misleading is it to refer to them instead as the king of France, and the kings of Austria, Prussia or Bavaria, because this insinuates, falsely, that they are something like the owners of all of France, Austria, etc.. And entirely misguided is it to call them the government of France, Austria, Prussia and Bavaria, as if they were merely the employees of the French, Austrian, Prussian or Bavarian population."
https://www.hanshoppe.com/2021/09/the-idea-of-a-private-law-society-the-case-of-karl-ludwig-von-haller-pfs-2021/#:~:text=A%20prince%E2%80%99s%20direct,or%20Bavarian%20population.