For me specifically: wireguard, strongswan (ikev2 vpn in iPhone), freshrss, paperless ngx, webdav server for iOS apps like genius scan and photosync, filebrowser for web access, archivebox, wallabag, airsonic, gitea.

Not the person you are replying to, but I host my local dev environments, HomeAssistant for various home automation tasks, Unifi controller, Paperless-ngx, Jellyfin media server, NAS and cloud backup of PCs, adguard, and occasionally some game servers for friends. There's a tremendous amount of self hosted software available for about any purpose you can think of though.