Can a person's PersonID be used to find all records related to them in familysearch?
In short, no.
There would be no way to connect the many records that are not indexed and even the majority of those that are indexed do not appear as "record hints" on the person pages of IDs, even when they seem to be very strong matches.
Also, remember there are a huge amount of records that are not linked to FamilySearch. In summary, you have to work very hard to find many sources that are available to be attached to the IDs in Family Tree.