Muscadine grape, one of my favorite fruits. My alma mater does a lot of work with muscadines, including making juice, wine, and ice cream. I did not participate in any of that work, so I cannot tell you exactly what variety of muscadine you have but probably a Nesbitt since it seems a little small for Jumbo or Supreme. But, I have no idea what varieties are available in Taiwan, if it came from there; I did not know muscadines were grown outside of the American South.
Unlike a jaboticaba, the skin is edible. Whether you eat it or not depends on your tolerance for sourness. Skin sourness is lessened in perfectly ripe fruits, but I eat them skin and all regardless. The skin is where all the good chemicals with health benefits are located.
They can handle the same amount of heat and far more cold than your average jaboticaba, and far more heat but less cold than European grape varieties. I am not sure whether they can handle Los Angeles's dry conditions, but you could experiment with them inexpensively by scarifying, cold stratifying, and planting the seeds.
Muscadines are readily available and pretty inexpensive in the South. I wonder if whoever you bought it from is intentionally labelling the inexpensive muscadine as the more expensive (presumably more expensive since I have never seen jaboticaba fruit for sale) jaboticaba to try and make a quick buck.