I agree. Public opinion would be in favor of neutrality ...
Most logical PoDs for US involvement reach back to 1919-20 & butterfly away WWII in general. ie: the US actually support France in enforcing the Versailles Treaty in 1923/24, or supports France in actively opposing the Rhineland occupation in 1936 & the Austrian Anschluss in 37. Even more likely is the US encourages a renegotiation of the Versailles Treaty in the latter 1920s. That has some positive economic effects and reduces German victim mentality.
Earlier in the thread folks touched on some extreme late 1930s PoD. Those involve near ASB levels of nazi foreign policy stupidity. Multiple actions that in the aggregate undercut the isolationist position. One such action would be for senior nazis like Goering to be even more kleptocratic and start nationalizing US businesses in Germany. i.e. Ford, Dupont, Chase Bank, Standard Oil (the Austrian oil exploitation) were all nazi friendly OTL. Seizing arbitrarily assets in Germany is not going to sit well with Henry Ford, or the Rockfeller family.
Another would be more aggressive and ham handed German intrusion into Latin America. Again that gets the nazis crossways with US business.
A third would be bungling the attempt to reach a treaty agreement with the USSR. OTL the Ribbetrop/Molitov Pact caused Moscow to press the Communists or leftists globally into neutrality vs the Germans. If the German/Soviet treaty is not signed Stalin may very well remain neutral in 1939, but he has less incentive to ask the leftists in the US to favor isolationism and neutrality towards Germany.
None of these individually would get the US into the war in 1939. All together & with other boneheaded moves the nazis could arraign it, but its low odds of all that occurring.