seb=# create function grant_all_on_table_to_user(s text, t text, u text)
returns text strict language plpgsql as $$
declare q text;
begin
  q := 'grant all on ' || quote_ident(s) || '.' || quote_ident(t) || ' to ' || quote_ident(u);
  execute q;
  return q;
end$$;
CREATE FUNCTION
seb=# select table_schema, table_name, grant_all_on_table_to_user(table_schema, table_name, 'user1')
from information_schema.tables
where table_schema = 'tt' and table_type = 'BASE TABLE';
 table_schema | table_name | grant_all_on_table_to_user
--------------+------------+----------------------------
 tt           | a          | grant all on tt.a to user1
 tt           | b          | grant all on tt.b to user1
 tt           | c          | grant all on tt.c to user1
( 3  rows)

seb=# \z a
                 Привилегии доступа для базы данных "seb"
 Схема | Имя |   Тип   |                Привилегии доступа
-------+-----+---------+--------------------------------------------------
 tt    | a   | таблица | {postgres=arwdxt/postgres,user1=arwdxt/postgres}
( 1  запись)