The Developer Portal now has a full documentation section — every feature walked through against the actual screens, with screenshots — and a Developer Portal entry in the site navigation to get you there.
The Seller Support Portal is live: raise a case with the API Platform team from inside the Developer Portal, track its status, and keep the whole exchange in one thread.
You can now browse the noon category tree, discover exactly which attributes a category expects, submit products against it, and read back their content — four endpoints, with a guide set that takes you from first call to go-live.