With the hdd i did a test on my xbox 360 and when i put a another hdd it put the version of when the console of the hdd so maybe you can use the hdd of xbox 360 and put a modded firmware and after you put the hdd it put modded firmware and before you all say "yes but it stupif you can't" its not...
btw i feel this a good time to remind you guys that sea of thieves was made by rare, who also made DKC1-3 and DK64, alongside banjo kazooie and conker's bad fur day