He runs a business repairing Apple products (independent, not authorised Apple). From memory I think he uses a piece of paid software which has them. He mentions it in one of his videos. I don't know where that company gets them. But Apple actively prevent spares being bought by end users. For example you can't buy OEM batteries or screens so he has to rely on non-OEM products. Apple recently managed to get US Customs to confiscate a shipment of batteries on the grounds that they were counterfeit. But the batteries were apparently clearly marked as non Apple products so not counterfeit at all. This is just one example.I've just been checking him out. Fascinating stuff. But where does he get all those Apple schematics from? They can't be in the public domain surely, so has someone gone through the hardware and painstakingly reproduced all the documentation?
In fact he also has a video on how he can source compatible non-OEM spares; when Apple design a new device they go to several manufacturers for parts and ask them to design and build some samples. Apple then choose one of the companies to supply them. But the other companies who also designed prototypes are now stuck with the cost of developing them and losing the contract. So to recoup their costs they still produce them but remove all Apple branding and hope to sell them to companies such as his.
His comments about the quality of Apple products and their restrictive practices to prevent users being able to repair their own devices, in the hope that they will buy a new phone/Macbook, have been quite an eye opener. I'm not sure I want to buy another product from them now.