Welcome to the community and thanks for posting your issue!
When you say facility ID, do you mean the org unit code? This is configurable in the Maintenance app so yes it will vary based on what the countries/organizations have configured it as in their instance.
I tried to find out whether you can change the display of the org unit name to the code instead in the Pivot Table but it does not seem like that is possible (tagging @dhis2-analytics to hopefully confirm or deny). You could choose to “show organization unit hierarchy” which will give you a bit more detail about the org unit, if that is what you are looking for.
You can get the OU code if you do an event report - line listing and download hat to Excel, if you are looking to use that type of report at some point.
Hope some of it was helpful and please do ask again if there is anything else!