The paper you linked is pretty succint and paints the battleground well. Brazilian agribusiness is state policy, but only the land itself and the commercialization of its labor can be said to be nationally owned. Inputs of all kinds comes from a number of different countries, while China is the main client by far. What immediately comes to mind is the situation of machinery and fertilizers.

The massive 'Others' under fertilizers means a number of middle eastern countries and Russia. Which explains some of the political pains that happened in Brazil when Bolsonaro was in power and Russia invaded Ukraine. There was this knee-jerk reaction to side with the United States (even though it was Biden who was president). But at the time Russia's trade hadn't yet been re-routed through China, so Brazil's political room for maneuver was limited.

Now with Machinery the US remains an important partner. But is it even an indispensible one for that matter? With seeds and fertilizers you can argue that medium term investments could enable onshoring in both sectors. But with farm equipment you probably wouldn't even need to do that since, I assume, China can just become the main supplier instead. This is where I think much of the political agonizing comes from. To sustain its agribusiness Brazil trades with every region of the world at once and there's very little keeping any one partner, most crucially China, from becoming a one stop shop for all the needs of the Brazilian elite.

It's good that you posted this because I don't want to give anyone the impression that Brazil has something akin to a 'national bourgeoisie'. We haven't had that since as late as the 1990s. Brazilian capitalists are happy to be junior partners of international production chains and secondary players in the financial markets. They are an aristocracy profitting from the periphery of global capitalism, and these two paragraphs from the paper you linked summarize this perfectly:

Specifically, this study reveals that multinational corporations established along Brazil’s soybean supply chain controls 91.3% of the seed, 99.8% of the machinery, 80.8% of the fertiliser, 94.2% of the agrochemicals, and 83.9% of the trading sectors. German companies control the seeds sector and have an important market share in the agrochemical business. Companies in the US control the machinery sector and have important shares in the agrochemical and trading sectors. Chinese groups have a relevant market share in the agrochemical and trading sectors.

As Brazilian groups control 93.4% of the farming sector, but only 7.1% of the agro-industrial sector, they should explore trade-offs between reducing investments in farming expansion into new agricultural frontiers and increasing their market share in agro-industrial segments. This study reveals two possible trade-offs between reduced farming expansion and increasing the industrial market share. The opportunity costs of hindered farming expansion can be offset either by an 11% domestic market share growth in the trading segment or by a 5.2% domestic market share growth in the whole supply chain. Domestic investments in the agro-industrial segments should be promoted as an alternative to investments in farming expansion into new agricultural frontiers.

Brazilian business culture is whatever was left after the country survived IMF sponsored austerity. And that was a best case scenario of sorts. When the sovereign debt crisis hit in 1982, industrial policy was largely dismantled for most things except agricultural expansion and plane manufacturing. This was part of the larger currency devaluation and export oriented strategy. It worked well enough to increase volumes, wreacked havoc on common people's purchasing power, but eventually paid some dividends in the form of massive commodity exports. Now nobody in charge wants to endanger those breadcrumbs. In part because they don't feel like the country can afford to compete in manufacturing or technology. In part because nothing is stopping them from behaving like international capitalists and becoming shareholders of the companies that supply them. In part agricultural industry is just not their business. Clearing more land for exploitation is.