Anything that came out when I was a kid or earlier is retro so anything pre 1990 is retro. Post is modern.

Pre smart phones there was a Bluetooth chat client for Sony Ericsson phones.

Have you tried Bluetooth Walkie ?

I’ve not used it myself, but the blurb on the Play store sounds like just what you need.

Do you think it would it work with dry products, including salt?

If so, that is a large percentage of packaging which this material can replace.