The platform is the trial in the Senate. Trump’s attorneys will be able to present evidence of widespread voter fraud.
Do you remember the last impeachment?
Any attempt to discuss Hunter Biden was ruled out of order, IIRC. This isn’t a normal trial. It is what the majority in the Senate says it it, and relevance is determined first by the one overseeing (Leahy), and then even if granted, can be over-ruled by a simple majority.
That will allow Trump to challenge Harris' authority to preside because she is not a Natural Born Citizen (vote fraud) based on the Senate's Resolution 511 (2007) stating McCain was a Natural Born Citizen because he was "... born of American citizen parents on a US Military Base". Harris is an unnatural born native with differing foreign parents subject to a foreign jurisdiction (countries issuing their passports).