I have two! The first is exotic purpose, the second is just tightly integrated so much that it might be only useful to me.

Smashcam

I live on a busy corner, in an otherwise slow and sleepy town right outside the city line. I live between a lot of town services on one side (fire house, library, athletic fields, town hall) and the elementary school on the other side. Pedestrian traffic is very high, the amount of children crossing is very high, bicycles abounds, and the cross street between them is decently high traffic.

So I see a decent amount of car accidents on my corner. 30mph limits on both streets so usually not catastrophic, you might be driving away instead of towed. But the repairs will be substantial on most of these. To provide an objective reality-as-a-service, I set up a camera high up in the eaves of my roof pointed right at the intersection. I’ve sent the police enough clips that they know where to archive my emails for evidence by routine. I’ve started training a model to detect car crash noises (and honks) to cut and save the clips automatically. It’s not reliable enough yet, but this could become a reasonable pipeline:

Car crash audio detected ->
Notification "Possible crash, do you want to review the footage and send to the po-po?" ->
manual human review to make sure we're not sending false positives ->
hit send ->
email with clip constructed and sent

Photos

This is not exotic in terms of its purpose. Lots or people have self-hosted photo sites (heres a whole chart of them all!)

But none of them integrated with my foss RAW editor darktable.

So I built my own photo site alternative that parses the darktable edit files and DB.

So now on the web, I can see the ☆ ratings I gave the photos in my editor. The tags and labels, etc. I parse the RAW files to show the focus boxes that the cameras write in the metadata when they took the picture, the facial recognition bounding boxes, etc.

And it shows the edit history stack and all the edits from my RAW editor. And of course, it has the left-right swiper to show before/after the photo edits. I can export any size, and it calls out to darktable with command-line control to export with the given edit stack to make the JPG of whatever size I’m requesting.

So yes, alternatives exist. Mine is simply very specialized to a particular editor program. I don’t believe I made the repo public, so as far as I know, I (and my family) are the only ones using it. It’s probably more featureful than things I have released.