we have a standard issue two tone wireless doorbell from the depot in our shop. its too bad 75% of people cant read the yellow and red 8" tall sign on our counter right behind the bell that says for help “ring bell”. people just stand at the counter and yell hello when were out back working.
i dont see how tricky it would be to have a hard wired one wired to a strobe light like a fire alarm. hard wired doorbells are dirt cheap. strobed fire alarms probably not.