About downgrade - you can host a static website in s3 directly, without a server at all. Maybe that's an option to explore. You can even use your own domain using a CNAME record.
You can push quite a lot on such machine. I used it as a shell access for my stuff from any place in the world, instant messages, IRC. Classic IM networks died so that part is gone as well, but a VPN like wireguard is a great choice.
A small monitoring system should fit.
A clean install of mariadb or postgress is around 40-60MB of RAM as far as I recall. This should open some doors as well.
A webdav/carddav/caldav server should also fit. I am about to check sabre/dav (sabre.io) software on a similar machine. So you can have a selfhosted calendar or access to your files on the go. Webdav can be handled by a web server directly (natively by nginx or apache etc).
I am recently charmed by Archivebox app, it makes backup of a website using multiple methods. UI is a custom Django Admin interface. It takes below 200 MB on my system.
A Teeworlds game server, if you are nostalgic towards quake but want a simpler experience for a break with friends.
Make sure to checkout the list at GitHub under awesome-selfhosted/awesome-selfhosted. Many, many inspirations there.
