Of these 55 vitamins, how many are essential? Only vitamin B(12), vitamin D, ω-3 fatty acids, calcium, iron, and zinc are a concern in vegan diets as far as I know, and these can be satisfied with proper supplements (https://academic.oup.com/ajcn/article/89/5/1627S/4596952)
> Beta carotene is nowhere near as effective as retinol That's true. It's about half as effective as retinol, when measuring using retinol activation equivalent (RAE). A baked sweet potato is more than enough to meet the RAE target suggested by the FDA https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/
> Vitamin K is basically non-existent in plants Vitamin K2 is non-existent in plants (except natto). K1 is found in green leafy vegetables in adequate amounts. https://veganhealth.org/vitamin-k/ For koagulation, both K1 and K2 are interchangeable. Though there are suspected to be functional differences in terms of bone health effects. In any case, K2 can be supplemented. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5494092/
> Vitamin B12 It must be supplemented. There are no good sources of vitamin B12 in plant foods, and we can't rely on gut biome to deliver it. But it's not impossible to supplement B12.