Please mods allow me a bit of background before going into the question itself!
Since I've studied quite a bit on the subject (although I'm no expert) I'd like everyone to know that today we celebrate the day when we decided to make our own very first national junta, taking advantage of a number of factors like the Spanish King imprisonment by Napoleon, and the economic allure that the english kept showing our forefathers, should we decide to break the spanish monopoly and trade with them.
It is a day when we decided to embrace the doctrine that says that "If the Viceroy rules because of the Kings authority, without a free king, the viceroy has no authority to speak of, so it comes back to the people" (doctrina de la retroversión) and named our very own representatives (curiously enough, the president of that First Junta was from Paraguay, Cornelio Saavedra). It was our first stepping stone towards our full independence which would come soon enough, on 1816.
But this subreddit is not just about history but also about asking questions isn't it? so here it goes:
To any experts out there, is it true that the south american revolutions of the early 1810's were funded and promoted in secret by the british? I see clearly that they would have had very strong reasons for doing it (getting more markets, having more commodities available for manufacture, expanding their influence on the South Atlantic since there was no Panama Canal yet, further weakening the decadent spanish empire, etc.), but are there any serious sources that say that they were actively involved, even in contact with some of the key revolutionaries from the time (Mariano Moreno, Manuel Belgrano, Artigas, Cornelio Saavedra, Juan José Paso, etc.)?
To my knowledge, no credible historians attribute the Argentine Revolution to secret British influence. In fact, the recent historiography has tended to cast the revolution more as a civil war between Spaniards (an idea developed by Jaime Rodríguez in his book The Independence of Spanish America) precipitated by the breakdown of the one Spanish institution that held their vast empire together.
Of course, many independence leaders had come into contact with Enlightenment thought from Europe, but creole leaders engaged with these ideas differently. For example, Mariano Moreno was fond of Montesquieu, Raynal, Voltaire, and Rousseau, but Tomás Manuel de Anchorena, educated alongside Moreno, never supported these ideas. These Enlightenment ideas were further shaded by elements of the Spanish Enlightenment, which tended to be more conservative and rooted in traditional and natural law. In the run-up to the Cabildo Abierto, there was a vast diversity of opinions about what should come next. Pro-independence leaders like Manuel Belgrano and Domingo French feared that their countrymen were not capable of independence in a republic, preferring a constitutional monarchy. They may have hoped that the British or the French would come to their aid, but it quickly became clear that there would be no outside intervention. At the same time, the Republican Party proposed a republican government that would be a better way of representing their interests than power resting in a far away monarchy…but this government probably should not allow everyone a place at the political table. When these two power blocs combined, it led to the break determined in the Cabildo Abierto. Thus, the Cabildo Abierto was a negotiation of power in which locals pragmatically determined, based on the information and understanding that existed at the time, what the course of action would be...renounce Spain first, then figure out what should replace it.
We can look at this question from another perspective as well. British involvement in the Río de la Plata is complicated, especially the early national period. As you mention, they have numerous reasons to be interested. They invaded Buenos Aires twice, were heavily involved in trading both legally and illegally, and had a reasonably sized immigrant population. Both locals and British investors benefited when trade restrictions were removed. As Nicolas Shumway explains in his book The Invention of Argentina, “because of England’s uncontested economic strength, free trade ultimately meant free reign for English capitalists and their porteño collaborators, regardless of the whole country’s best interest.” This has led some to call Argentina an informal member of the British Empire. However, direct British rule was categorically and swiftly rejected by the people of the Río de la Plata following the invasions. Additionally, British trade quickly fell off following the removal of trade restrictions. There just wasn’t a particularly large market for their products in an area whose primary economic activity was subsistence agriculture. Agricultural production would develop into the agro-export economy that took hold in the 1850s and catapulted Argentina onto the world stage at the turn of the twentieth century, but that was still 40 years away. As Alan Knight writes in his article “Rethinking British Informal Empire in Latin America (Especially Argentina),” “trade briefly boomed in the 1810s, then stagnated (in monetary terms). The British came to realise that, even if an independent republic was preferable to Spanish colonial rule, it still fell far short of expectations.” Investment would not pick up again until the 1850s.
So in short, I don’t know of any backroom deals or conspiracies to break apart the Spanish Empire hatched by the British. Though they had a great deal of influence, the British had neither the resources nor the influence to implement such a plan. The only possible argument might be found in the Enlightenment thought which motivated independence leaders, but even here, independence leaders engaged with it with a high degree of agency. Instead, independence, both the successes and failures, belongs to the local leaders who had the courage and audacity to embark into a brave new world.