Default answer for Americans: “Yes it is still illegal, technically it’s smuggling, assuming it’s not a controlled substance.”

Nuanced answer: There is a loophole where Americans can get medicine from overseas if it is the exact same drug/brand/dose as their prescription AND the imported drug was produced under FDA supervision and is labeled for sale in the USA. This used to be a situation where you could get big discounts for the same brand name drug but now they have different brand names for different price markets and they don’t distribute the FDA drugs to India/Turkey/etc or do so at the same wholesale price; so this loophole doesn’t help much. You might find 10-20% discount off domestic retail price but not 80-90%.

Not a lawyer, but AFAIK if one has a valid rx for e.g. adderall, it's still illegal to make it (or even to buy it from a friend who got it via their own valid rx). I'd expect the situation to be similar.

Yes, otherwise everyone with a prescription that costs more than a few dollars a month would be ordering from these services and US pharmacies & drug-makers would go out of business (or be forced to cut prices dramatically)

[EDIT] As pointed out by another poster, unless the drugs are valid for import to the US and such and it's all done above-board—obviously, the US doesn't manufacture all its own drugs. But those aren't the cheap options.