I once set up https://laminar.ohwg.net/

It has the special quirks that it’s configured outside the repository and script based. Listening for webhooks from forgejo needs an additional service though. (Like https://github.com/adnanh/webhook)

Demo: https://ci.ohwg.net/

https://dontkillmyapp.com/

I’m still not sure that filter thing is necessary. FreshRSS can fetch content and images using the CSS selector of the website. You may want to check out the Advanced section in their documentation: https://freshrss.github.io/FreshRSS/en/users/04_Subscriptions.html#retrieve-a-truncated-feed-from-within-freshrss

Anyway, whatever works for you :)

What’s the extension for? FreshRSS can fetch contents natively.