You can get just how long it will take in total and subtract the time left. You can get the total time by dividing the time left with the percentage left
This is why I use a USB C stick instead. But Android is getting abit too locked down for things at large in regards to that so??? I guess we just have to deal with this late 90s protocol Microsoft made for mp3 players on our Android devices that have already been replaced by better solutions like on Symbian where it still hid files but pretended to be a USB stick.
"I have been migrating files since the (fourth) Crusade."
Backed up my iPhone to the computer, not the Cloud. Any transfer I still do using the Lightning cable connections, not Wifi. "You have chosen... wisely."