Shitty as it was, there was no third or fourth option to be had; once Harris was in the driver's seat, it was going to be her or Trump, simply by the way our political system is set up. With that in mind, going forward, all questions would have to boil down to "Is it preferable for Harris to enter into the presidency, or Trump?"
If it's election-time in 1930 Weimar Germany, and my only viable choices in the election district I'm in are the SDP and the Nazis, banging the drum 24/7 on how the SDP is anti-LGBT (true) might not be the greatest choice in the coming election considering that the only other choice are the Nazis, who are MORE anti-LGBT plus a whole host of other horrific things. And if the Nazis themselves are beating that same drum, telling LGBT folk that the SDP is anti-LGBT, I might step back and consider whose electoral victory I'm contributing to by my rhetoric and what consequences it will have - such as on, say, LGBT folk.
We're sitting here with literal fascists in government. "Our aristocrats weren't good enough, or didn't take the correct stance on foreign policy!" isn't the correct answer to why this election turned out the way it did. Or if it is, that reflects such a broken attitude on the part of the American electorate that it's not much better than the actual conclusion - most Americans do not care if fascism comes into power. And that includes everyone who didn't vote, or protest voted. And many of those who didn't vote or protest voted were inspired to do so by rhetoric encouraging apathy from both conservatives and their useful idiots.
Should the Dems have done a whole host of things differently, including having actual primaries? Are the Dems spineless corporate weasels? Are the Dems beholden to Israeli interests even in the face of a divided base? Yes, yes, yes. But none of that justifies "We're going to let or help the literal fascists win."