I was able to copy a 16gig zip file in minutes to my laptop from a 3 year old android phone. Why is it taking 10+ hours to then copy the files to my Graphene OS new phone? Copied both using various cables, including the USB-c that comes with the new Pixels. Same behavior.
Copying files from my computer to Graphene is PAINFULLY slow
You could try KDE Connect, it works very well and is available for many platforms.
https://kdeconnect.kde.org/
My experience is different - copied over 7Gigs very quickly. About the same speeds with GrapheneOS as with stock Android 13.
MetropleX Intel(R) USB 3.10 eXtensible Host Controller - 1.20 (Microsoft). Have tried with a USB hub connected with a SSD plugged in. I've also tried with the sole phone connected to the USB c port. The latter option does give me 3 hour estimate as opposed to 10+ hours. Also, when accessing a large folder, 10 gig plus full of media, it takes several minutes for Windows Explorer to load the files (not just the thumbnail preview) in the window.
I've had slow copy speeds to USB drives using the AOSP Files app, but I've had far better speeds using Ghost Commander or Cryptomator with a vault on a USB drive. So I personally never copy/move stuff with Files if I'm moving/copying something outside of the phone's internal storage.