Where I live the surplus is shipped over the border or even overseas if there isn’t enough demand here.

Because there is more demand there, which is influenced by individual behaviour. As you have said, the production in ones country won't just end if enough people decide to limit their consumption, but this only applies if there is enough demand elsewhere, and the demand elsewhere depends on the consumption of the people living there. Their actions will decide how much will be exported to them, and they are as responsible as anyone else. This ignores that "other markets" likely have a poorer population, because most of the consumption is happening in western countries. One person reducing their consumption in the USA has a much larger effect than 10 people in Cuba doing the same. It isn't symmetrical, and therefore can't be that easily replaced. Either way, this applies to all people where possible anyway.

The overwhelming majority of consumer goods are shipped in across the pacific. So it’s not like we can stop the production by not buying them, the factories will just ship them to somewhere else and sell there.

Your argument seems inconsistent. You say that consumer behaviour affects export and demand, but also argue that it makes no difference because it would be shipped elsewhere. If individual behaviour can lead to goods being produced for another market instead, the people there have the same power. This logic only works if people elsewhere start consuming more because you are consuming less. What would happen if everyone consumes less? Exactly! Less production. Covid has shown that just this year.

Now on the subject of plastics I don’t know where you’re at but it’s not possible to walk into a grocery store on a budget and not come out with a cart full of plastic containers. When people have a fridge full of plastic it’s not because they dgaf about the earth, it’s because they can’t afford to buy the expensive stuff. Or that they live in the USA and everything is packaged in plastic and there isn’t another option.

In all my posts I have emphasised that this only applies if people choose to do so while having other options. I have lived in the US for a bit, and you can definitely get relatively cheap produce that isn't wrapped in plastic. There are valid reasons why you wouldn't be able to cook etc., but the vast majority of Americans could certainly consume less, lol. It doesn't stop at food. This is not even debatable. There is no other nation with as much mindless consumption.

Production does not go down due to small fluctuations

What I am talking about would lead to more than a small fluctuation. "My actions don't have any impact" is just learnt and accepted helplessness to be more comfortable with your own selfish actions. Which is funny, because this comes from the people who consume as much as 50 people in poorer countries.

But let’s say that wasn’t true. Someone who makes the decision to only buy locally grown grass fed biodynamic beef can’t be considered a 200iq rational actor who should be shamed for their decision to participate in climate change even a little bit as a treat because they’re affected by myriad influences to normalize that consumption.

Of course, that behaviour is even incentivised by bullshit "environmentalism". People live within a system that not only normalises this kind of consumption but actively encourages it. Maybe even add a few symbols on the packaging that make the buyer feel good about their purchase. But people are still able to make choices. If you are aware of the situation and choose to not care and tell yourself some excuses ("my actions don't matter", "everyone does it"), as is the case with almost everyone here, then I am not going to only blame the system which they act within.

Also here in the USA meat trade organizations have a history of astroturfing demand to justify increased production after the fact and to whitewash safety, ecological and health concerns.

Yes, they are evil. I never said they aren't the worst actors.

it’s why we can’t rely on individual choice to change production

Unfortunately we can't. If we could, we wouldn't be in the current situation. My argument was never that individual choices are the driving force behind climate change, but that individuals are to blame for their (conscious) actions that drive climate, and that individual choices have an impact. They are immediate actions that have a positive effect collectively. Telling people that their consumption does not matter, especially when most people here are Americans, living in the by far most wasteful nation, the biggest contributor to climate change, is just harmful, and false. Advocating for responsible consumption is good and important. It will have to happen anyway.

The comment I replied to was about a kurzgesagt video btw. The user said that they were arguing that the consumers are at fault. This shows the tunnel-vision so many people here have. The video said that what anyone can do, immediately, is to be less wasteful. Afterwards the video talked about taxing emissions etc.