CMV: The "Republicans for Harris" stuff was very poorly executed
The idea was fairly simple, recruit a bunch of high profile Republicans to support Harris over Trump, an unprecedented number compared to past campaigns. In doing that, the Harris campaign was pretty successful, they got the Cheneys, Kinzinger, Flake, and a lot of others. The problem though is that was all they did.
My view is that there were two roads that Harris could've taken to run a more successful campaign, lean hard into centrism or completely abandon the big tent. Going back to when Biden ran, there were a lot of high profile Democrats who thought he'd gone too far left with trying to pass the $3.5 trillion BBB on party lines. Joe Manchin, Krysten Sinema, and Jon Tester all publicly said this, and Joe Lieberman even started an effort to recruit a centrist alternative to Biden. If Harris had leaned harder into centrist policies (i.e. by being more supportive of Israel, and not supporting abolishing the filibuster or introducing higher capital gains taxes or taxes on unrealized gains).
If Harris actually shifted on policy in a centrist direction, she could've won more moderate independent/skeptical Republican votes, but she didn't. She decided to not tell the DNC to run a mini-primary, and she picked Walz as her VP instead of Shapiro or Beshear. She campaigned with Republicans, but that was all she did, even the Republicans who campaigned with her didn't talk about policy, they just gave the same bland "Trump is a threat to democracy" stump speech, it wasn't enough in my view to actually to create an actual "Republicans for Harris" bloc. Time and time again, one of the Trump campaign's main strategies for criticizing her was by highlighting pre-2020 examples of her supporting leftist policies. No one was convinced by the centrist act.
But even as a centrist myself, I have to play devil's advocate, and I could see the "Republicans for Harris" stuff turning off a lot of further left voters too. Imagine being someone who voted for Bernie in the primaries last cycle, and now your nominee is campaigning with a Cheney. On some level that has to be disappointing, I don't want to get too anecdotal, but of all the people I know who supported him or Warren or who are even somewhat progressive/further left, I can't think of any who would respond positively to Harris and Cheney campaigning together.
TL;DR, I think the "Republicans for Harris" effort was very poorly executed. I don't think it actually won over any people in the center or center-right because it didn't involve any real changes to Harris's policy positions, and I think it was discouraging for a lot of people on the left as well to see their nominee campaigning with a well known Republican.