I got an archive of Dilbert comics, mostly as GIFs, from the Internet Archive and needed a viewer. I used the tools in utils to rename all the files to just an ISO-8601 date, and then if you can statically host those, it's easy to use a Javascript frontend (index.html) to look at them. I used an S3 bucket for my copy, you can use whatever you like for yourself.
There's a live demo at Dilbert Website 2000.
You can send an archive image to a Slack webhook every day using the bundled webhook_doer.py script. Use a cron job or systemd timer to run it every morning.