I'd have to become more familiar with news publications and everyday usage in Argentina and Cuba. The best I can do is remember how the family code was passed via a democratic dialogue across the island, as opposed to a more top down disposition - which is what I expect from Argentina.

Brazil could have the same style guides in it, but I'd expect minimal purchase amongst the population as it (like everything else) would be a top down political project. Besides, odds are the vast majority of the population wouldn't even know about it. By sheer inertia gender neutrality is baked into the context of speech, the masculine being generally used, and if someone even knows about 'Latinx' or 'Latine' odds are they are online and a redditor (and have very strong opinions about it, both for and against). Of course, the advantage goes to the house, as in the people who don't want something changed.

At most what would happen is if the school system started using -e as gender neutral as opposed to o(a) and a(o) for it's forms and then the kids would assimilate it. But that's 2 generations of work.