At first glance, the connection between these mitzvot and the Land is not clear, as Don Yitzḥak Abravanel comments on the prohibition of interest:
We must not think that the phrase "on the Land to which you are coming to possess" indicates that the prohibition is dependent upon the Land, since it is a general and permanent command.
In order to understand the connection between the Land and these mitzvot, we may cite the opinion of Naḥmanides, based upon Midrash Sifrei, that observance of mitzvot is primarily within the Land of Israel, and the comment of Netziv [Exodus 20:12], which elucidates Naḥmanides' approach:
Nonetheless, mitzvot are uniquely connected to Eretz Yisrael, and for this reason they are called "the law of the God of the Land." [II Kings 17:26] It is understood that even though the mitzvot are relevant outside the Land, they are still primarily connected to the Land.
Thus, on the general level, all 613 mitzvot have a special connection to the Land. However, we may suggest that each of the three mitzvot mentioned above has a special connection to the Land.
The common denominator of the prohibition of interest and that of maintaining differential weights is social justice, which is a foundation possessing the Land, as we read in the previous parasha, Shofetim:
"Justice, justice shall you pursue, that you may live and possess the Land the Lord, your God, is giving you." [16:20]
Concerning the prohibition of remarrying one's divorced wife after she has married another, the Torah teaches that the Holy Land is more sensitive to immorality than all other lands, as the verse in the portion of incestuous relations states:
"And the Land became defiled, and I visited its sin upon it, and the Land vomited out its inhabitants." [Leviticus 18:25]
Thus, each of the above mentioned mitzvot indeed has a substantive and special connection to the Holy Land. (David Magence)

Shabbat Shalom
The Va’ad