I believe Biden is a sincere peacemaker. As I recall, Biden also agreed that he was wrong to use the term bullseye.
First off, it's inaccurate to say Trump is literally Hitler, since Hitler is literally dead. Secondly, saying Trump is an existential threat to democracy and saying he is like Hitler are in some ways two different things. The similarities of note are that both Hitler and Trump have shown to be powermongers who both use fear and negative prejudice to appeal to their cause.
The claim that Trump is an existential threat to democracy actually has a completely valid point of reference because, as a sitting President, Trump tried to get Pence, his Vice President, to reject the valid votes of the people and overturn a fair election so that Trump could stay in power. We shouldn't blame Democrats just because they can clearly see that Trump was willfully trying to get others to undermine the ethical procedures under the laws of our Democratic Republic so as to hold on to power. Remember that the definition of a powermonger is a person who wields power in a tyrannical or irresponsible fashion.
And it's not just Democrats. Mein Kampf is a well-known manifesto which I have read. I know other people who have also read it, and we all were remarking that Trump sounded like Hitler because Trump was expressing similar sentiments of negative prejudice about migrants, using the same phrases that Hitler used about Jews. I think J.D. Vance even mentioned that Trump was like Hitler.
"Fearmongering" and "to the left" are mischaracterizations. I am compelled to say that we need to sincerely try and not promote nor entertain slander. It's wickedness to even want to believe bad about others.
Having said that, it's not wrong to speak the truth based on observable facts. In reality, Trump actually did use his position as President to try and overturn the election based on the deliberate lie that it was stolen from him. He even tried to get the justice department without any evidence to imply that there were indications that the election results were questionable. It is also true that Trump did use Hitler type of remarks to express similar sentiments of negative prejudice, and it's also notable that prominent Neo nazi leaders have expressed support for Trump.