It’s been a long time since we executed anyone for treason. In 1953, Julius and Ethel Rosenberg were convicted of passing nuclear secrets to the Soviet Union during the Cold War. They were executed in the electric chair. However, even at the height of Cold War tensions, their execution was controversial. As for hanging, it was William Bruce Mumford during United States War of Independence in 1862.
As for the players in the J6 insurrection, it was the instigators put out by the government for their false flag effort that should be charged for treason.
There is precedent, so controversial or not, it should be available as the consequence of selling state secrets and treason.
"As for hanging, it was William Bruce Mumford during United States War of Independence in 1862."
By 1862, it is likely that anyone committing treason from the War of Independence would have likely already become a worm buffet, but again, there is precedent for hanging traitors. Mary Surratt unavailable for comment (noting no gender specific punishment).
"As for the players in the J6 insurrection, it was the instigators put out by the government for their false flag effort that should be charged for treason."
And promptly hanged once the wide array of evidence is made public and proves their guilt beyond any fathom of reasonable doubt.
Quite a few others since Mumford. Tried by military courts, and also by civilian courts.