Impeachment may be shaped like legal process, and the final act may be called a “trial” and supervised by the Cheif Justice, but its a political process, and the difficulty of proving things “in a court of law” is pretty much irrelevant except to the extent that comparisons to a court of law may be provide political rationalizations for actions in the impeachment or trial process.
(IIRC, one version of the bill of impeachment had a second article related to Abuse of Power with regard to the Georgia election call, but that was eliminated in favor of making the issues regarding the call part of the context for the insurrection charge, rather than a separate charge.)
Proving criminal liability is not required[0] in an impeachment trial.
"President Trump’s conduct on January 6, 2021, followed his prior efforts to subvert and obstruct the certification of the results of the 2020 Presidential election. Those prior efforts included a phone call on January 2, 2021, during which President Trump urged the secretary of state of Georgia, Brad Raffensperger, to “find” enough votes to overturn the Georgia Presidential election results and threatened Secretary Raffensperger if he failed to do so."
https://www.congress.gov/bill/117th-congress/house-resolutio...