I’d be fine with tags in the digiKam DB including all of the above, but the values written to the images IPTC keywords field would have to be limited to the subkeys of what you listed above as type and content hierarchies. Here’s an example of one of my images: https://www.flickr.com/photos/tcgoetz/53265234720 you can see what I use for keywords in the info below the image.

My workflow also includes grouping similar images, using compare to grade them best to worst, marking the best with the pick flag, and rejecting the worst. I also group subimages of panoramics with the generated panoramic as the top of the stack and the pick image. didKam has a group feature but it seems different. Grouping in LR hides members of the group other than the pick image.

In my workflow tags == keywords which are orthogonal to albums. Keywords describe a photo and get published with the photo. One photo can be in multiple albums like Flickr Photosteam (published to Flickr), “Zion Vacation” (event album, published to Piwigo for friends and family consumption), “2022 Year in Photos” (yearly highlight album), “Favorite Landscapes”. Photos are in a date hierchary on disk.

DigiKam has come a long way, but it’s still missing some really basic DAM features. I’d love to stop using Lightroom and there are plenty of good raw converter replacements, but it’s the DAM features that there are no replacement for. In DigiKam an album is a directory on disk. A photo can’t be in two albums at once. They recommend using tags for more groupings, but that just seems clunky.

TLDR: “Billionaire Elon Musk’s decision to rebrand Twitter as X could face legal challenges due to existing trademark rights held by companies like Meta and Microsoft for the letter X.”