I was thinking about this today. In older comics we see Peter give a Spider Tracer with a special boosted signal to Mary Jane for emergencies. He gave similar devices to Betty Brant and Flash Thompson in Hobgoblin Lives.
But as far as we know he never gave anyone else this sort of security measure? Okay, maybe we could presume he gave one to Aunt May when she used to know his identity.
This raises the question of why did he never as Spider-Man or as Peter Parker (whom people know knows Spider-Man somehow) try to give Betty, Flash or any of his friends Spider Tracers for safety earlier or afterwards?
The real reason is the writers didn't think of doing that but I am looking for an in-universe/No. Prize attempt here.
All I got at the moment is that they were too difficult to make in large numbers/he didn't want to raise suspicions too much.