In California, you don’t get a choice
I distinctly remember voting in that election, in that specific race. And on looking at it again, the electorate clearly had a choice. And in the general it wasn’t even a choice between Harris and an outright Republican. It was Harris or Sanchez (who as you point out is also a Democrat, at least in name).
Harris won by around 61% to 38%. Sanchez was a blue-dog, so she invariably garnered the votes of conservatives who voted in that race (the general). But Sanchez still lost convincingly to Harris.
And in the primary? Harris won handily there too. She and Sanchez smashed the ever-loving shit out of the opposition (38% and 18% respectively). The third place Democrat came in with just 2.2%. Yes, Harris has a very large war chest for that race. But regardless, a lot of people voted for her in both the primary and the general.
This narrative that Harris was forced on Californians without any say is false, and honestly it’s disingenuous. Yes, the party framing the election in a way they wanted had an impact. That’s how party’s work, not only in California, not only in America, but all over the world. But you don’t stroll to victory like Harris did purely on funding. If there was a genuine appetite for a hard-left candidates in CA they would have done much better in the primary. But they didn’t. The simple fact is that despite what some (both inside and outside for California) say, the state’s electorate is fairly moderate and pragmatic overall.
Edit: typo fix and minor clarification.
As I pointed out before, I’m talking about the 2016 Senate race. Because it shows that Harris was a viable political candidate in California then. And she’s clearly still a viable candidate here based on recent polls.