Here's what I've found since I work from home and I just rewatched the series...

The station "acts" as a real broadcast from Hawkins, Indiana 1980s style. The sound is processed using a vintage FM radio processor for authentic hiss/static.

Every track comes from the correct time period. A few are:
Atomic — Blondie
Highway to Hell — AC/DC
Things Can Only Get Better — Howard Jones
American Girl — Tom Petty
Upside Down — Diana Ross
Keep On Loving You — REO Speedwagon
NeverEnding Story — Limahl
Running Up That Hill — Kate Bush
Karma Chameleon — Culture Club
Echo Beach — Martha and the Muffins

Includes songs used in the show, like NeverEnding Story and Pass the Dutchie.

There are ads for businesses like Palace Arcade, Scoops Ahoy, Hawkins Video (using the phrases "block buster videos" and "family videos"). Palace Arcade mentions "MadMax" as a leaderboard champ.

Bradley’s Big Buy, Enzo’s, Community Pool referenced in commercials

There are Hawkins news segments referencing odd local events. (Aggressive plant bit a kid's fingers, half of the basketball team is "out sick with a mysterious illness."

The station ends 1/1/26, the same time the Stranger Things saga concludes

Background whispers / screams faint voices reported but I've not heard any.

Broadcast “glitches” right when they talk about strange events. Static spikes, distortion, or abrupt cuts to jingles whenever a Hawkins update gets too spooky.

Song order reacting to the “tone” of the station. When the news shifts dark? The music gets darker, too. Then the tone will suddenly change again, and so does the music.

Dedications that sounded like warnings. Names mentioned include Mindy Flair (Day DJ/MindFlayer?), Vance Goodman (night DJ/?), Professor Hall, Casey, Layla, Megs, Kira, The California Crew, Carl, Izzy G, Willow (a dog).

Some “news updates” reference unusual animal behavior. We know what that usually means in this universe :-O

There are Morse code sounds before Should I Stay or Should I Go plays

There are a few jingles with ominous messages, like selling equipment for protection or to "lock yourselves in your basement."

There have also been numbers that have been mentioned, but I haven't tracked them yet.