My spouse and I each play on the PC version of the game.
We have two accounts each, and two computers each, for playing.
Each account (of four total) has it's own SE/MogStation account and subscription.
We can play any account on any PC, just be logging in using the desired account.

We also have an Xbox series X console hooked to our 65" UHD OLED TV.
Right now we mainly use the Xboxfor streaming and playing UHD Blue Rays.

If we bought FFXIV for Xbox, would it be tied to only one FFXIV account, or would we have the same ability we have with a PC, that is, we'd able to play any of our accounts from the couch in front of the TV?