The only supplement you can't get from a vegan diet is B12, because farming is too clean (it is in dirt, and eating dirt is how you'd get the B12 needed). Everything else you can get from eating plant based products.

You do not need heavily processed oils and grains nor do you need a variety of supplements. Beans and Rice contain all of the necessary proteins a human body needs for example.

B12 deficiency is an issue even for people that eat meat due to the cleaner practices and feeding where animals no longer graze but instead get their food delivered in a way that doesn't allow the animals to ingest the B12 from the dirt.

You can absolutely survive eating food that is not cooked with oil.