@RJungwirth
Hi. Perhaps check out the SVG icon range from sources like: https://feathericons.com . Some SVGs are open source to use. But do check the usage licence conditions for your particular use.
In the Publii demo at: https://demo.getpublii.eu/themes/q-answer/1/ , they may have used the ‘Bookmark’ icon from a source like the one above. But you can choose any SVG you think is suitable.
Once you have downloaded an SVG icon, in Publii, create a new tag, name it ‘All’, then add your SVG icon using the ‘Featured image’ option. Next, add the ‘All’ tag as an additional tag to every single post.
