They key here is that "the perimeter" tends to be where the less-processed (and more perishable) foods are.
Exceptions which are internal, as you note: spices, oils, coffee (and/or tea). I'd add:
- Frozen fruits and vegetables, particularly if you want to buy bulk and reduce spoilage. Rapidly-frozen foods can be higher in nutrition than "fresh", most notably vitamin C, which degrades relatively rapidly.
- Bulk grains, legumes, and nuts. Other baking supplies as well, which are typically on interior aisles.
- Tinned goods, including fish. Prepared soup stocks. Arguments for/against canned goods exist. There are long-shelf-life goods which make much preparation easier or provide for easy and healthier snacks.
I too can spend years without walking down a crisps / snacks aisle.
Among foods which may seem healthy but often aren't: many breakfast cereals (overly-processed, low-fibre, high-sugar), numerous freshly-baked goods, sweetened yoghurts (plain is generally fine), fruit juice (liquid sugar --- eat whole / frozen fruit instead), many "diet foods" (often trading fat for sugar, overly processed, and overpriced to boot --- see Polan's basic dictum).
I'm not saying "never buy / eat these". But do so rarely, as special occasions, and do so consciously. For the most part, I don't miss such ... food-shaped products ... at all, the few I do sample occasionally I appreciate when I do.
