rtcary2 wrote:
I have an Apple multiport adapter and I was using it on an Apple MacBook to pass Thunderbolt AV through the USB-C port the signal of an Owl through the USB-A port since the MacBook only has a single USB-C port. The USB-C port will not past the Thunderbolt 3 signal. I guess the port is only for charging, which I have done.
The Apple USB-C Digital AV MultiPort adapter is not a Thunderbolt device. You can connect it to a Thunderbolt 3 port or Thunderbolt 4 port on a Mac or iPad, but it only uses/supports USB-C (DisplayPort, USB, Charging).
It has three ports: HDMI, USB-A (USB), and USB-C(Charging). The USB-C port is a power input port ONLY. It is not a Thunderbolt 3 port, or even a USB-C (USB) one.
USB-C Digital AV Multiport Adapter - Apple
is there a splitter for two USB-C inputs for a MacBook with only one port?
If your MacBook has only one USB-C port, that would make it a 12" Retina MacBook. Apple released those in Early 2015, Early 2016, and 2017. All have USB-C (DisplayPort, USB, Charging). None have Thunderbolt. So you'd need to look at docks that use USB-C but that don't use Thunderbolt.
I bought one of the OWC USB-C Travel Dock Es for a 12" Retina MacBook.
Other World Computing – OWC USB-C Travel Dock E
Other World Computing – OWC USB-C Travel Dock
Both have two USB-A (USB) ports, a HDMI port, a SD card reader, and a USB-C (pass-through power input *only*) port. The E version costs $10 more and adds Gigabit Ethernet. You could connect a USB-C (USB) device to either USB-A (USB) port, though I believe neither of the USB-A ports will run at faster than USB 3.0 ("up to 5 Gbps") rate.
There are also a ton of USB-C-only docks on Amazon and in brick and mortar stores.