I'm DIT on a shoot getting footage from a bunch of different sources. I'm using a MacBook Pro with 2 Thunderbolt 3 ports. Ii've got a hub that connects to those 2 ports and has 2 Thunderbolt 3/USB-C ports plus 2 USB 3 ports (plus some other useless at the moment stuff). The problem I am running into is when I try to take stuff off a USB-C drive and copy it to both my Master and Backup drive (USB-C) at the same time or if I want to copy from a USB-C drive to my Master drive and charge my Macbook at the same time there are obviously not enough ports. I cannot seem to find any products that can turn 1 USB-C capable of data transfer into 2 or more. This really has to exist doesn't it? Any help would be greatly appreciated.
Just came across your post, so thought I'd add my thoughts.
I've been using the CalDigit TS3Plus dock for some time now and I think it would do what you ask (along with stuff you may not need) as it's come with a hefty PSU to power any MacBook and free up some ports by giving you one full speed USB-C (Gen 2 10Gb), one USB-C 3.1 Gen 1 ( 5Gb/s), 5 USB-A 3.1 plus Ethernet, card reader, display port etc.
So I think you could plug your Backup drive into the dock, then your source from the front usb-c or the spare one on your MacBook.