Were any South or Central American nations besides Brazil involved (not necessarily officially) in either of the World Wars? If any were, I'd appreciate information on their degree of involvement.
Yes, both World War I and World War II involved South and Central America.
Here is a list of South American countries that severed relations and those that declared war. Sourced from here.
Although eight other South or Central American countries declared war, only Brazil had direct involvement. Brazil sent surgeons and pilots to Europe. Most pilots served with the RAF, but some served with the French Army. Brazil was mainly involved at sea, however. A good part of their fleet was involved in anti-submarine warfare. However, there we're quite a few delays that hampered the war effort:
World War II also saw some South and Central American participation. However, again, Brazil was the only nation of these to send troops to fight.
This organization was instrumental in organizing the nations of South and Central America. In fact, before the founding of it, some of these nations recognized Manchukuo as a legitimate state.
Argentina was officially neutral, but leaned to the side of the Axis. After the war, many war criminals harbored there.
Chile also was officially neutral, but later joined the Allies
Before 1940, "Costa Rica, El Salvador and the Dominican Republic offered diplomatic recognition of the Japanese puppet state of Manchukuo which was not recognized as a legitimate state by a majority of the world’s nations at the time." Note Dominican Republic is North American.
So, yes, there was involvement from South and Central America, but it did not play an instrumental part in either of the World Wars.
"Mexico and Brazil were the only Latin America countries to play an active part in the war, both on the Allied side. At their peak, the Brazilian armed forces in World War II numbered 200,000."
"Among the pro-Axis Latin American countries, pro-German feeling was strongest in Argentina, including solid popular support for the Nazis. Argentina had a large German population and an even greater Italian one....In both Chile and Argentina there was suppression of pro-Allied opinions and support."
Terror and Triumph, By Marshall Cavendish
The South American countries were very hostile to the Axis in World War II and displayed it strongly, even though most did not send troops.
Costa Rica declared war on Germany on December 4, 1941 days BEFORE Pearl Harbor (counting on the Monroe Doctrine. Mexico declared war in April 1942, Brazil in August 1942. Colombia authorized the creation of American bases anywhere on its soil. Brazil, Venezuela and the U.S. worked on joint defense plans for the shipment of bauxite (used in ironmaking) from Dutch Guyana (Surinam). Later, these included the shipment of Venezuelan oil and Brazilian foodstuffs. German submarines were a threat in the Caribbean and even the South Atlantic.
Some 21 of the original 34 signatories of the (anti-Axis) United Nations were in the Americas.
Argentina maintained diplomatic relations with Germany until March 1945. Germany ran a clandestine air bridge to Argentina via Barcelona and Villa Czneros until the very end of the war.
Gottfreide Standstede and Wilhelm Seidlitz at Delfino Shipping were responsible for an Abwher smuggling chain through Spain to germany to defeat the Allied blockade.