After using Pinboard.in for several years I noticed that I basically only ever use the features described above. Also while I like the minimal approach and the quick UI of Pinboard, it could just look a little bit nicer. So I took that opportunity to make a hobby project out of building such a service myself while also learning something new. I decided on Python and Django as stack, as I never really used Python and Django looked impressive. Building the application took me around 2 weeks. I implemented the features above, added a basic CSS framework with minimal tweaks so the UI looks nice and made everything work on mobile. My take-aways from the project are that Django is really awesome. Django is a batteries-included web framework and provides pretty much everything you'll ever need OOTB. The documentation is among the best I have ever seen. Also as someone who has been mostly working on SPAs / rich clients for the last decade I have to admit it was a sobering experience how quickly you can get results with an integrated server-side framework like this. I'll definitely consider that approach more from now on.
If you are interested, the application is basically ready-for-use and easily installed with Docker. I have been running it for 6 months now in a Docker container on my Raspberry Pi and in terms of just dumping links into a storage it suffices for me. I provided a demo instance with open registration here: https://demo.linkding.link