Hi,
maybe some of you are interested and this could be helpful 
TL;DR
digiYiiKam is a browser-based gallery, which shows the albums from digiKam in the browser.
It is free and open source and help/contributions are very welcome.
GitHub: GitHub - patschwork/digiYiiKam: Web frontend for the famous open-source software DigiKam Photo Management
(screenshots, installation, roadmap, …)
Setup:
- Dedicated MySQL database (on a server) for digiKam.
- A central location (file share) for all images.
- Requires a server that can run PHP or at least Docker.
Background / Motivation
I searched a lot for a webgallery, which stays (or some sort of) in sync with my digiKam albumns (album structure, tags, comments).
The primary requirement was viewing on the smartphone (and on the browser).
I always had a jealous look to the people, which are using the Adobe Cloud and are in sync and can browse their images while not having all the pics local on the smartphone 
.
Leaving the path “Try 1”: PhotoPrism
Great project! Very hard work and much effort and love goes into this!
The scan for images was some sort of slow on my server. Also I don’t have the need for auto-tagging (AI) features. The navigation was not the same as in digiKam (other concept)… Also I gave up at some point to sync the metadata.
Leaving the path “Try 2”: Piwigo
Same as a PhotoPrism: Great tool! Great community and many plugins and addons.
The web gallery is really fast and has a good performance (on my server). Piwigo offers an app for Android (and iOS) - also a new modern app based on Flutter.
Sadly, it is not feature complete, but on a good way.
The downside:
- All pictures must be mirrored to Piwigo.
- No way of automatic syncing from digiKam to Piwigo (the plugin for digiKam to upload works, but has also some drawbacks itself e.g. no de-duplication).
- Tags (digiKam / Piwigo) must be synced on an way outside.
Other galleries…
I tried a lot. But didn’t find any solution. There are also some projects which aims the same: A digikam gallery. But all of them seemed to be “dead” (on GitHub) when I searched.
Sad of all, many galleries does also not support RAW files from camaras… 
Creating a new tool: DigiYiiKam
Then I decided to build a new tool.
Main requirements
- Don’t replicate the images (as far as possible - see below)
- Stay in sync with digiKam (show metadata and tags). Keep master data in digiKam.
- Ability to use it on a smartphone (may be an app in the future)
- Navigation based on album structure and tags (may more in the future)
Downsides
- A second database (to keep the digiKam databae clean and reduce dependencies)
- The preview/thumbnails files from digiKam can’t be reused. It’s a file format, which can’t be displayed in the browser and a conversion on the fly was out-of-scope. Therefore JPG files are generated for RAW files like CR2, CR3, NEF, DNG, … which will be used for display in the browser. Existing JPG files will used as is.
- Thumbnails will always be generated for all files.
- Videos are not supported, yet
It’s been working pretty well for me for over a year now so I thought to share this here.