I have a KVM that is able to share a single USB2 port between up to 4 computers along with the keyboard mouse.
You can drop a file from a Windows PC onto it and read it from a Mac connected to the same KVM. It's pretty cool.
Cost about $100 on Amazon for the 4Port version with 4K support. I have a MacMini + Windows + RaspberryPI + Nintendo Switch connected.
The trick is that normal KVM's disconnect the ports as you switch between hosts, but this model keeps the ports alive so the O/S doesn't lose / rediscover the keyboard/mouse/usb each time you switch.
I've tested the port with a USB2 stick, PS4 controller and a Logitech mechanical keyboard which needed more power than the dedicated keyboard usb port on the KVM.
Don't want to break any advertising rules, but if you google the product, it's red.
My first answer, so YMMV.
Not an answer, but SCSI could do this, with some caveats. From 2004 https://criggie.org.nz/scsi/
– Criggie – 2019-07-05T13:09:36.973