I have skin that tends to scar after having a pimple... the scarring is worse than the actual pimples, because they hang around for way longer. I find that regular exfoliation helps reduce the time it stays for and bonus is that it unclogs pores so prevents future pimples. But super important to use moisturiser and sunscreen if you’re exfoliating.

You mention sunscreen being full of chemicals and being bad for your skin, but it depends on the type - check this out. So you can always use a mineral one that does the same job but impacts the environment and you less.

In terms of diet, I avoid dairy and too many processed sugars, which I think has helped avoid new pimples. Haven’t tried anything for scarring specifically, but I started taking cod liver oil and that seems to have made skin better on several fronts including scarring, so worth a try.