Wild yeast and bacteria are everywhere. However most wild cultures don't do a great job fermenting wort. A wild mixed culture will typically yield apparent attenuation in the 50-60% range, which is a lot lower than brewers yeast. This means your wild beer probably will be more sweet, and have less alcohol.
The stuff in your photos is characteristic of wild yeast cultures. That is to say, they're unpredictable. It's nothing to be worried about. One of my wild cultures looks pretty much identical to that, with the stuff floating at the top -- however most of mine don't, so my guess is that maybe all your cultures contain similar microbes.
How did you introduce wild microbes?
Yeast can form pellicles, not just bacteria. Since your culture contains wild yeast and bacteria, the appearance of a pellicle would give you no information. Just don't be surprised if a film forms on top.
PET fermenters do not let through an excessive amount of oxygen. They're perfectly fine to use with beer regardless of what yeast culture is used.
The bubbling in your photos clearly indicates that yeast have fermented your wort. You can determine the ABV with a hydrometer, if you measured the s.g. of the wort before introducing your wild culture(s). If there's any way you can get a hydrometer, I'd strongly recommend it.
Lactobacilli? If your beer is sour, then possibly. However there are many genera/species of lactic acid bacteria so there's no way to know if there's Lactobacilli specifically without further analysis in a laboratory.
It's totally fine to use wild yeast to make beer, but you'll need to be careful when you bottle it because over time the level of carbonation may increase.
Also, it will very likely have the flavor of beer that most of us recognize as "Belgian", as opposed to non-phenolic yeast most commonly used to make beer throughout the rest of the world including the Americas.
Unlike wort, wild yeast will fully ferment any kind of fruit juice (or diluted honey or agave) up to a reasonably high amount of alcohol.
Sorry, I'm not really sure which Mexican fruits might make a good wine. If you can extract sweet juice from a fruit, it will possibly make a good wine.
Maybe give these guys a call to see if they could send you a Homebrew quantity of yeast:
https://www.difusa.mx/
Their website doesn't list any of the yeast products unfortunately.
Hope this all makes sense. I'm happy to answer any questions you may have about wild yeast or bacteria.
¡Salud!