Spanish citizens legally resident in Catalonia benefit from the political status of Catalans or citizens of Catalonia.
Is it possible for a foreigner to get the same status ? If yes, how long does it take ?
Yes it is possible through
Spanish naturalization, which requires 10-year residency in the most general case.
On the other hand, municipal registries (instead of the civil registry) will probably source the list of voters for November's independence referendum. This means that foreigners who can vote on local elections will be able to exercise their self-determination right and decide the future of Catalonia. Symbolically, this makes them members of the Catalan People by the very definition of popular sovereignty.