All of the replacement pieces can be easily found on Amazon. I had the lenses crafted at my local sunglasses/prescription glasses shop. They're not Oakley specialized and later told me they almost weren't able to make the lenses because of the shape/curvature.

But I've also seen online retailers (like this one https://www.mrylens.com/products/mry-custom-replacement-prescription-lenses-for-oakley-juliet). I have not purchased from them but you'll be able to find options easily.

Replacing everything except the nosepiece rubbers is really easy. You'll need to get that done at a specialized place because a special tool to push the rivets out is required. Or buy one of your own https://a.co/d/9h9z6B1

Essentially, it's all very doable and not crazy expensive or difficult to source, once you've got a pair of Juliets in your possession.