If I understand correctly, you don't want to setup it yourself and maintain the server, correct? In that case, you can use hosting, provided by miniflux developer: https://miniflux.app/hosting.html
You can try https://miniflux.app/hosting.html to check how it works in real life (screenshots are outdated a bit and don't show dark theme or other useful stuff)
May be you missing something, but miniflux can get full content automatically, you just need to set mark "fetch original content" [0] when creating or editing feed.
By the way, it allows you to set custom grabbing rules [1] for original content, very useful when website has ad blocks or useless elements in article body