Gah! What a waste of time! So frustrating!
OK, so here is what I have so far:
If I change the "date modified" in Windows and then transfer to Linux, Linux will keep it so, even though I cannot change it in Linux I can always take the file to Windows, change it there and transfer back to Linux.
BUT
transferring from Linux to Android (phone) the date is lost and Android sets it to the current moment.
I downloaded and installed
File Timestamp_v3.05_apkpure.com.apk (2.6 MB) which is supposed to do what I want but, besides it being cumbersome and confusing, when I try to do anything I get an error message that
This feature requires root permission. Your device does not have root permission enabled.
It does seem to identify the correct timestamp and I am guessing it gets it from EXIF.
What say you?
E.T.A.: I guess another possible solution would be to have Android sort the photo files alphabetically which should work because the file names are all in YYYYMMDD_HHMMSS format.
It seems
File Timestamp requires me to "root" the phone, whatever that means, but I read that can be dangerous. I don't know but it seems to me they make things unnecessarily complicated.