There were a number of plants and shipyards that were seized both before and after Pearl Harbor. The Selective Service Act of 1940 permitted seizure of manufacturing facilities where the owners refused to give preference to Government orders or to accept them at reasonable prices as determined by executive officers. The President's role as Commander in Chief also gave him an ambiguous justification to seize industries necessary for the war effort.

That being said, FDR and the government went to far lengths to avoid seizing businesses. Seizures were sometimes unpopular with labor, and were always unpopular with business interests. For the most part the government sought to reach compromise between companies and labor. Prior to Pearl Harbor they had formed the National Defense Mediation Board (NDMB) to mediate labor disputes and it proved to be hugely successful, even getting Henry Ford to accept the United Auto Workers (UAW) at his River Rouge plant in Dearborn, MI.

The threat of seizure was often enough to affect compromise like it did at the Allis Chalmers plant in Milwaukee, WI which manufactured turbines for destroyers. There were still three plant seizures prior to Pearl Harbor.

The first was in June 1941 at the North American Aviation in Inglewood, CA. 2500 US Army soldiers with fixed bayonets cleared the picketers and seized the plant. Workers quickly came back to work, and the army would oversee the running of the plant for three months before the NDMB negotiated a raise for workers and the government returned the plant to the owners. One of the main reasons FDR sanctioned the seizure was that the strike was called by local leaders, and national UAW and CIO leaders were opposed to the strike so there was no risk of offending labor.

The next seizure in August was of Federal Shipbuilding and Dry Dock Company in New Jersey. The labor dispute in this case was owner refusal to declare it a union shop and fire workers who refused to pay union dues. The workers cheered the seizure by the navy and immediately resumed work, although the navy didn't formally engage in collective bargaining in their own shipyards. The NDMB was eventually able to negotiate a maintenance of membership agreement and returned ownership shortly after Pearl Harbor.

The final seizure prior to Pearl Harbor was of Air Associates Inc. plant in Bendix, NJ. Air Associates manufactured landing gear cylinders and other aircraft parts. In this case the government convinced the company's board to fire president F. Leroy Hill who had fired a number of union workers and replace him with an executive of their choosing before returning control.

After Pearl Harbor there was a lull in seizures as national spirit seemed to calm the waters at least during 1942. Also the NDMB had been replaced by the more powerful National War Labor Board (NWLB.) 1943/44 saw a couple dozen seizures, although seizures were just as likely to be due to managerial incompetence as opposed to labor strife. Consolidated Aircraft, Savannah Shipyards, Brewster Aeronautical, Triumph Explosives, Howarth Pivoted Bearings Company, Los Angeles Shipbuilding and Drydock Corporation, and York Safe & Lock were all seized for managerial incompetence and either had their management teams replaced or placed under the management of a larger firm before being returned to private ownership.

There were also a number of businesses seized due to labor strife, but these were normally smaller companies. Most of the larger strikes managed to be quelled either by the NWLB or threat of seizure. The biggest such strike was of coal miners and the United Mine Workers which almost ground railroads and steel production to a halt, but was eventually resolved.

The longest seizure was likely that of the smallish Toledo, Peoria, and Western Railroad company which was seized in 1942 and ran by the Army until the end of the war after the owner got in a pissing contest with the NWLB. Even after returning the company to the owner, George P. McNear, after the war he continued to battle labor and was eventually murdered in 1947.

The threat of seizure was usually enough to force compromise between business and labor, but labor strife began to be a problem again by mid 1943. This led to the passage of the War Labor Disputes Act or Smith-Connally Act (over Roosevelt's veto.) This required a thirty day cooling off period on would be strikers where they were required to register their intentions with the government, wait 30 days, and hold an election on the intent to strike before actually striking. It also banned union contributions to political candidates and made it criminal to strike against a seized plant. Furthermore it mandated return of the plant be returned to the owner within 60 days of resuming normal production although that was hardly concrete. Other methods helped deter strikes such as denial of raw materials and cancellation of draft exemptions.

In the end, seizures were rare and usually fairly short-lived, but they did happen.

Sources:

Wilson, Mark R., Destructive Creation: American Business and the Winning of World War II.

Heinrich, Thomas, Warship Builders: An Industrial History of U.S. Naval Shipbuilding, 1922-1945

To answer your "in part" question, I'd also recommend Richard Overy's "How the Allies Won" which spends some time looking at the voluntary compromises and consensus building around war production goals. Including a remarkable scene where soon after Pearl Harbor the CEOs of major industries met with a government official and they sat around a table saying things like, "OK, Ford will build this jeep, Dodge will build this tank, we'll share this foundry to cast engine parts," and so on. This system of cooperation for war industry is a big reason why u/jayrocksd lists relatively few seizures or nationalizations.