Christoph I think it would be nice to have an optional second home-button on the left of the other button (maybe just a house-icon without folder) that leads to the main url of the site.
I'm not sure about adding another button in the "breadcrumbs" nav. It doesn't seem obvious, and we kinda need to control the flow and design of that element from the application. Instead, I was thinking of making it possible to add custom buttons in the topbar (where the filter and layout buttons are) ... Or perhaps include a custom topbar (above the filter and layout buttons) where you could include a logo ...
Christoph I think that many people will use the app as gallery in a subfolder of their website.
Indeed. Files gallery will always emphasize functionality (file manager / file viewer), and will therefore be slightly limited in regards to design and customization. I do have plans to create a "website gallery" version of Files ... Similar concepts, but with more options for design, colors, fonts and customization.
There is already embed.files.gallery (based on Files.gallery), but this is really just a script to embed single galleries into existing website pages.