You can’t really do it in a way that’s compliant with USB specifications. USB is a purely point-to-point connection, a cable like this that offers even a minute chance of having three or more devices connected to the same conductor is just asking for all kinds of trouble. Even with just two devices, there have been issues with non-compliant USB-C cables causing damage; no reputable brand is going to risk making something even more complicated. If you need to deal with different connectors, you’re just going to have to carry multiple cables; such is life until we finally get everything on USB-C.

In terms of pure math, CPU and GPU cores are actually pretty equal. However, GPU cores lack a TON of other essential features supported by a modern CPU. For example…

Features needed for secure multitasking:

• Protection rings
• Virtual memory/paging
• Virtualization

Features needed to manage the system’s hardware:

• Programmable interrupts
• Memory-mapped I/O
• System Management Mode

Features needed for high performance in workloads that aren’t massively parallel:

• Simultaneous multithreading
• Branch prediction
• Out-of-order execution/register renaming

GPU cores are pure math machines with minimal capabilities outside of that. CPU cores are multipurpose monstrosities that spend surprisingly little of their time adding numbers together (and most of the addition that does happen is just calculating memory addresses).