Though not necessarily in the spotlight at the 1938 Wilmington, Delaware celebrations to commemorate the 300th anniversary of New Sweden, Finland was definitely a part of the ceremonies.
For example, at the Wilmington ceremony, Doctor E. Rudolf W. Holsti, Finnish Minister of Foreign Affairs, delivered an address as part of the festivities. It began:
"On behalf of the Finnish Government I have the honor to greet all the Finns and Americans who have come from far and near to celebrate the memory of the early Finnish Colonists and their permanent settlement in the Delaware River Valley 300 years ago.
I am happy to avail myself of this opportunity to calling your attention to the excellent relations existing between Finland and the United States as well as to the numerous bonds which unite our countries. The memory of the Finnish Delaware colonists we are now going to celebrate will, no doubt, also tend towards strengthening the ties of friendship between our nations."As did Sweden, Finland marked the anniversary with a stamp issue and by striking a commemorative medal; unlike Sweden, Finland did
not issue a commemorative coin. Finland's commemorative issues were intended to highlight its contributions to the settling and development of New Sweden.
Finland New Sweden Commemorative Stamp
Finland New Sweden Commemorative Medal

The medal was designed by Alpo Sailo (1877-1955), the noted Finnish-born sculptor and painter who was known for the realism portrayed in his work.
Four figures are seen on the medal's obverse: at left is Klas Larsson Fleming (1592-1644), a high-ranking statesman who served under Swedish King Gustav Vasa; he served as the King's representative in Swedish Finland (Finland was part of Sweden at the time). He was also an admiral in the Royal Swedish Navy. Fleming was born in Swedish Finland and continues to be a highly-regarded historic figure in Finland to the present. At Fleming's left (viewer's right) are presented a Finnish man, child and woman (l to r, respectively) in period clothing. They are meant to be representative of those who traveled to the New Sweden colony in the 16th century.
"SUOMALAISIA TALONPOIKIA AMIR KLAUS LAURINP FLEMING / 1638 - 1938 encircles the figures at the rim. The Finnish inscription translates to "FINNISH PEASANTS ADMIRAL KLAUS LAURINP FLEMING".
Portrait of Klaus Fleming
(Image Credit: Image courtesy of Nationalmuseum (Stockholm). Public Domain.) On the reverse is depicted the colony's settlement with its log fortress and church in the background, and a newly-cleared field for farming in the foreground. The ability to construct log structures (including cabins) was a valuable skill set brought to the colony by the Finns. Also seen In the foreground field is seen a tree stump and roots (at left), along with bundled crop stalks.
The inscription "DELAWAREN SIRTOKUNNAN 300-VUOTISMUISTO" encircles the design at the rim. It translates as "300TH ANNIVERSARY OF THE DELAWARE KINGDOM".
The medal's edgel features "LYÖTTÄNYT SUOMEN TASAVALTA" which translates to "THE REPUBLIC OF FINLAND".
The bronze medal has a diameter of 57 mm, and a weight of ~80 grams (~2.8 ounces).
1936 (-38) Delaware Tercentenary Half Dollar

To learn more about the Delaware half dollar, check out:
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1936 (-38) Delaware Tercentenary-
1936 (-38) Delaware Tercentenary - Senate v. Senate v. House-
1936 (-38) Delaware Tercentenary - Official BulletinsI've also written about multiple other "cousins" of the Delaware commemorative half dollar, you can find them here:
Commems Collection.