I made feed-repeat for myself. I wanted a tool to send me old blogposts written by my favourite authors so that I could enjoy them again, but also not be overwhelmed by a wall of hundreds of unread old posts. feed-repeat does just that.
It can be self-hosted easily using the provided NixOS module or systemd service. It can also be made to run entirely serverless on GitHub Actions/Pages using the provided workflow. The website contains detailed docs and guides.