It's pretty trivial to gather all the ingredients for the non-Wasteland smoothies without ever leaving the forest. Mushrooms, aloe and blueberries can be easily farmed, coal isn't particularly a problem, oil shale is available from those big cylinder oil storage POIs, snowballs are available from scrapping ice machines. Water is obvious, and I can't recall if there are any other ingredients, but they're certainly not anything tough to come by (I say this from experience, not just theory.)
Now, the Wasteland smoothie taking radiated mushrooms, acid, and super corn (which is a pain, but thankfully Rekt seems to always sell seeds/actual super corn) is quite a bit more challenging.