AppleInternal is apparently used by Apple for internal development purposes, and thus likely has no benefit or reason to be installed on an average users Mac. Why it is included on some macOS installations with new Macs (and apparently some reinstalls too) is a bit of a mystery, since these are not Apple employee computers.
To delete AppleInternal from the Mac, you can open the Terminal application and issue the following command at the command line:
sudo rmdir /System/Volumes/Data/AppleInternal
Enter your administrator password and press Enter.
Then, you should reboot your Mac and the /AppleInternal directory will no longer be there.