A 'Coup' is "a sudden, violent, and illegal seizure of power from a government ". Check, it was an attempt to take control of the Capital building and prevent the ratification of the electoral college.
I don't think this can be considered a "seizure of power", not even an attempted one. For one, you have no evidence to suggest that this was the motivation of the mob. Neither did they have any sort of organization or even the weapons necessary to overpower the security forces that were there, nor did they even try. The only shots fired inside the capitol were those by the Capitol Police.
So you can't say that they attempted to seize power, because you have no evidence for that claim.
Fascism is "a form of far-right, authoritarian ultranationalism characterized by dictatorial power, forcible suppression of opposition and strong regimentation of society and of the economy " Check. Forcible suppression of opposition. They tried to force Democrats and Republicans to violate the Constitution and prevent the ratification of the electoral college.
Again, you have no evidence as to what they "tried" to do. In fact, evidence points in the opposite direction. Taking silly pictures at desks and wearing viking costumes, and inviting someone's grandma, are not the actions of people who want to "seize power" or force anyone to do anything.
Black Lives Matters and Antifa and what they do or did has NOTHING TO DO WITH THIS.
I'm bringing them up to demonstrate the double standards between what happened here, and what they have been doing.
If X, Y, and Z = terrorist, then other groups who do X, Y, and Z must also be terrorists. This is unavoidable. You cannot have one without the other. Do you disagree?
It's not whataboutism. It's forcing you to recognize that you can't just toss accusations around without consequence.