Also Louis Rossmann channel where he repairs Macbooks while ranting about Apple.
He'd also need the same software they have access to though to provision a new T2 chip ...
The only problem is when a particular component is really prone to failure and becomes rate limiting, while having no 3rd party supply.
(Ie: a burned out resistor is easier to swap than carry a full part count of every combination. While a custom chip that fails is really bad news).