Transferring Xbox One Games on Hard Drive to Xbox One X

At least from what I was finding on the network, if you can transfer games from the hard drive from an xbox one to an xbox one x

Hey there Slikyboi Uk x! The
Hard Drive Transfer Cable is a great tool for moving data from one hard drive to another. =)

Not really...

Xbox Series X games / upgrades / updates has to be installed onto the Series X internal or expansion card SSD,

You can have Xbox One games on your external hard drive that will get an Series X upgrade but the games will need to be transferred to the Series X and then the Series X upgrade will need to be downloaded onto the Series X SSD,

As an example...

I have Marvel Avengers on my external hard drive that will get the Series X upgrade and I will transfer the game over to the Series X SSD ready to download and update the game to the Series X version when available.

You can transfer content between the two sure. You would do it the same way it can be done on the current Xbox One S and X.

You may not be able to transfer everything as the expansion is 1TB and your hard drive may be larger than this. You won't need to transfer everything anyway as the hard drive can still load Xbox One games, it just won't be able to load Series X/S games.

The loading performance you'll get will vary per game. With Open world games benefiting the most.

I have a gaming PC with a modest speed SSD. On Assassins Creed Odyssey it takes 6 seconds to fast travel between locations in the game world. On my Xbox One X it takes 40 seconds!

I'm almost positive you can if you have the hard drive space but not at the same time. Plug one of the hard drives in the hard drive bay. Then plug in your empty hard drive into the transfer cable then the transfer cable to one of the usb ports on your xbox.
Transfer the data and repeat for the other hard drive. That should transfer all the data onto one hard drive. Hope this helps!