Technical reason: A USB-C device must be driven by a USB-C 'uplink' port in the PC. Since your PC does not have a USB-C port, no USB-C device can connect.
Therefore, I'd suggest adding a USB-C card such as a $19 card from NewEgg, or a $25 card from Amazon. Both connect to PCIe slots on your desktop motherboard, so please check that you have the necessary ...
The cheap route is to use a USB-C Hub. I have used this one across many devices and can vouch for it.
The fancy way, you can get a USB-C Dock that is basically the same thing but is meant to be stationary, so has its own power supply and more functionality.
Both of the above options would turn your desk into a generic "Work Station" at ...
USB-C hubs with power pass-through are fairly common. Often sold with the Power Delivery (PD) mark followed by the power rating for that device. Here is one such hub that I use regularly to connect peripherals and charge simultaneously. However, this hub does not have a USB-C slave connection.
Hubs that also have a port for a USB-C slave device are more ...
I think you can use this one from amazon: https://www.amazon.com/Adapter-Monitor-Display-Docking-Charging/dp/B08BYJYC5K
According to the description, it supports extending your desktop over USB-c, but it only works if you have thunderbolt or DP alt mode on both of your laptops. Your monitors need both displayport and hdmi for it to work properly, because ...
If you search for "KVM Switch" on Amazon, that will get you part of the way to your end goal. The one I use only allows 2 input computers to go to 2 monitors. For some reason they do not sell these at stores like Best Buy and MicroCenter so results may not be perfect depending on you Hardware/Operating System set up.
There is no USB-C splitter come out this year because there is not single produced chipset for USB-C Splitter/Hub.
And if your laptop using USB-C for charging input there, the data pin is locked automatically because it was for reading voltage and making it to lock the pin for setting data input or voltage input in charging mode.
Explanation in USB-C pin:
I recommend Logitech's MX Master 3.
Internal battery, with USB-C (and fast charging!)
Bluetooth and USB dongle support
Cross-platform support; Bluetooth works on all systems with support for Bluetooth mice. Optional configuration software is supported on macOS and Windows.
7 buttons, vertical and horizontal scroll wheels; vertical scroll wheel ...
You can simply buy an external Hard drive case plus a hard drive of your choice.
For a 3.5" drive, I've found this two options:
Unykach UK 35303
Then, you can attach any 3TB, 4TB or 6TB 3.5" drive you wish.
In case wou want to use a standard USB 3.1 enclosure, you can easily find USB 3.1 to USB C cables.
A lower capacity solution but ...
Instead of something hard to find how about
Note the separate power supply connector on the back.