Looks like you're hosting this on fly.io - PAYG model. You could probably host this for free on Cloudflare Workers; 100k requests/day on the free tier; static content (the homepage) is free & unlimited.

Edit: The catch is the 10ms CPU cap per request - you'd need a super lean implementation. Django's too heavy for that.

Well, someone already did with JS: https://github.com/ProfessorManhattan/rss-worker

Python alone is many milliseconds to start. Unless they give you some allowances for interpreter overhead.