Get the underlying foreign key constrains based upon a view
You can check which tables are used by a view using this statement:

select vtu.table_schema, 
       vtu.table_name
from information_schema.view_table_usage vtu 
  join pg_class cl on cl.oid = (quote_ident(vtu.table_schema)||'.'||quote_ident(vtu.table_name))::regclass 
where (view_schema, view_name) = ('public', 'test');


If that returns only a single table, you can query the system for foreign keys referencing that (single) table.