If you happen to have a Mac, the easiest way to export all your stuff from Photos is probably osxphotos. It has an export command with options for downloading everything from iCloud, exporting originals as well as edited versions of photos and you can split the export into one directory per album as well to simply transfer existing albums.

I’ve been using chilipie-kiosk for a few projects. It‘s easy to set up and I‘ve never encountered any problems with it.

It‘s basically just a lightweight Debian installation which launches Chrome in fullscreen mode on startup, opening either the preconfigured URL or the one that was open at the end of the last session.