I think you are spot on with explaining the perspective of the Democratic party campaign strategists, but I would push back on some of those points.
Remember that the stock market is important to these voters (and his donors), and Trump had everything set up in his favor and still squandered it.
I don't think they see it that way and honestly using the same "objective" metrics, removing 2020-2021 due to COVID being a major outlier, there isn't much difference between the Trump and Biden presidencies from an "economic perspective". If you include 2020-2021 it looks like Trump "squandered it" and Biden had "unprecedented growth" but it's really a story of outliers and how they can be manipulated to tell whatever story you want.
It's also needs to be said that those "objective" metrics have/are becoming increasingly divorced from "objective" reality but that's a conversation for a different thread...
Corporate America does not want a repeat of this
Trump was great for Corporate America, Biden has been even better. The MAGA propaganda is that 'Trump really stuck it to corporate America and was actively working against their interests' or 'he might suck but at least he's hitting the corporations where it hurts them most' but I really haven't seen any good evidence for any of that (see the point above). If you've got some counter evidence to share I'd be interested.
convince some Republican voters who would have voted red "because that's what you do", to instead vote for Kamala.
But they won't any more than you'll convince many Democrats to vote for Trump. Those voters that the Harris campaign is targeting will be voting Libertarian, Green or (mostly) "holding their nose" and voting Trump.
Honestly, one of my biggest annoyances surrounding the Nader spoiler controversy is the assumption that all votes would've gone to Gore where the evidence does not support that conclusion and it's subsequent use as a cudgel to support duopoly instead of the more accurate warning of what happens when you sacrifice your voting block to pander to the other half of the duopoly.
it's easy to forget that just because they're Republican's does not mean they are MAGA
You're right, and within that context it may be useful to use the self identify method the house tepublicans use ("the House Freedom Caucus, the Republican Study Committee, the Main Street Caucus, the Republican Governance Group") to discuss who "is MAGA", who Harris is pandering to and play the fun game of 'which of those 5 groups is the lesser evil?' and look at the ven diagram between those...
The "solid Democrats" of the last 4+ years have been putting people into ~~camps~~ ~migrant detention centers, prisons, enhanced interregation facilities, any other euphemism for camp that doesn't come with the same baggage~, stripping legal protections and significantly reducing access to medications.
The "existential horror shit" does not stop with this election, regardless of outcome.