Facebook Messenger log exporter tool (as of Nov. 4, 2017, I'm not sure if this tool still works. Facebook likes messing up their internal API from time to time...)
ChaosEvoker/html-to-pdf seems useful (since phantomjs can't handle the extremely large HTML files I'm creating) but insists on pure XHTML which is annoying. I'm working on making a version that uses danfickle/openhtmltopdf which should be much more flexible.
As of now, for animated stickers such as the Pusheen set, only the static image is downloaded. (Photos, stickers, and other images sent in a conversation are downloaded to be rendered into a static HTML down the road)