Well… There is no such thing as an “average minimum sales in general” when you are starting out making games. You will need to work a regular job to support yourself for at least the first few years. I wouldn’t want to be too disheartening, but your first few (free) games won’t reach more than maybe a hundred people. Even when they are free, people might simply not have the time in their day to check if the game they downloaded 3 month ago is any good or not and then they might simply forget. I would say that, here on itch, a better metric than sales is followers - especially when you’re starting out. Those are the people who would ask “What has Argenis Rodriguez been up to?”, rather than stumbling over your current new game by chance. At this moment in time, there were 60 new, paid releases over the past 7 days and 73 “free” ones (which users could still donate for) on itch.io alone. That is what you would be competing with for attention - at the moment. And in my personal, limited experience, as game development becomes more and more accessible that number will always rather go up than down.
If you want to know about expected income for an employment as a software developer in that niche… That is a question that you should forward to Venezuelan game devs. You wrote about the difficult legal situation, which will probably be a factor. And I wouldn’t know the first thing about Venezuelan taxes. ;)
A bit of advice in that regard: Try to look up interviews with independent developers before you contact them. Even if your questions weren’t answered you might be able to reference that interview, showing (or underlining) that you actually care about what they have to say and didn’t just write the same mail to 20 studios. If you’ve written bug reports or fan mail to any devs try to contact them first. There’s a chance that they would remember you.