Is there some good material on protectionism from a Marxian perspective?

Unsure of this, but would also like to know if anyone does happen to have something.

If only the US was using protectionism as a measure to maintain high wages in its factories of internationally overpriced commodities, that'd be a pretty good thing, right?

It wouldn't work long-term. They'd cut the workforce down to the minimum skeleton crew needed to run production and overwork those people. Plus, with China being more competitive in both quality and price, they'd be overtaking US equivalents regardless. US industry itself is dying, and it's irreversible. The falling rate of profit demands lower quality for higher price tags, and the US hasn't been investing into R&D on a level anywhere close to the Chinese, so they have no future in this race.

China's Great Firewall functions as a digital protectionist measure to foster a domestic tech industry that isn't dominated by FAANG like how the internet developed in the rest of the periphery.

Well, here's the thing about the Great Firewall: Yes, indeed it was so they could foster a domestic tech industry, but it was also a strategic move to attain sovereignty in their information space and protect them from Western manipulation in China's internal affairs. See this relatively short video here. It's not so similar in that with EVs, people need reliable transportation to survive in the West as they have no high-speed rail networks. With the price of gas, auto repairs and maintenance always going up, these EVs could liberate working class people from dependence on much of the US' fossil fuel and automaker giants, which the US absolutely will not tolerate.

The US demands a population as desperate as possible to reduce worker bargaining power, increase employer leverage, and maintain their monopolies.

But it seems like there's a lot of nuances here, like how the West uses protectionism to maintain hegemony.

That's entirely and always what this is about.