I would be concerned about things like diacetyl and other nasties too. To be honest, you might find something that is safe, but flavour-wise most are very disappointing. Griz has a recipe using ASDA Rum flavour - I tried it and it wasn't one of his best flavour mixes I tried.
The only non vape specific flavours I use are Nielsen Massey coffee and vanilla extracts which give detail on what's included and the percentages. And I use these with non aqueous VG. I also steep tobacco leaf, vanilla pods and coffee, but that's a whole different thing.