There was something back in the OS 9 era that did this. It might have simply been called Holiday Lights. I remember as a college kid really enjoying having them enabled this time of year.
Holiday Lights is still alive and well. Not as many features as the original, but it has been updated to work on modern macOS. It's now 'MacLampsX'. I am rocking it as we speak (see screen shot).
I like the lights to just be on top with a calming twinkle and a steady flow of light snow, of course. And these are incandescent-looking classic lights, not the cold and ugly LEDs that we are mostly subjected to today in both real life and apps. I reached out to the developer years ago wondering whatever happened to this app and he said he was thinking about resurrecting it, and he did!
I miss the good old days when a bit of whimsy was built into most apps and operating systems with theme and icon packs and novelty software such as this. Anyone remember
Stick Software? Eyeballs still work on modern macOS! There were so many fun and goofy apps. Catz? Dogz?
The 90's and early 2000's will always be my favorite internet (wild wild west) and Mac era (even vintage PCs). What I would give for someone to update the entire After Dark Screensavers collection and re-release it. Berkley Systems was acquired and folded into a Sierra division after After Dark 4 was released, and their parent company killed most of their titles (including most of Sierra eventually). It was never even updated for WindowsXP and it never worked in OS X. There are a few modules out there that will run on modern versions of macOS, but it's just not the same, of course.
Nowadays GUIs are so cold, boring and stoic. Apple, the pioneers of beautiful icons completely destroyed them and now we are living with ugly tile icons, many are just glyphs slapped onto tiles, and to add insult to injury, we cannot change most of them. Remember Candy Bar? Why can't we have nice things anymore?
Anyway, I like that you can add lights onto the dock, so I will of course give Festivitas a go.