"Youlag Theme for FreshRSS" provides a video-focused browsing experience for your RSS subscriptions. It tries to provide a similar experience to YouTube, primarily through its layout using CSS, but also a little bit of Javascript.
Git repo for more details: https://github.com/civilblur/youlag
In case you're not aware, "FreshRSS is a self-hosted RSS feed aggregator".
The idea is that you subscribe to content creators through YouTube's RSS feed https://www.youtube.com/feeds/videos.xml?channel_id={id_goes_here}, then browse, watch, save to playlist ("label"), right within FreshRSS.
There's also third-party extension for FreshRSS that provides the ability to use Invidious, but as we all know, the public instances are unfortunately struggling quite a bit as of writing.
I have limited knowledge of what limitations extensions have at the moment, but considering FreshRSS is server side rendered, integrating DeArrow on a deeper level would be ideal (if possible). It would mean that the thumbnail and title you get when you load the page would immediately be the non-clickbait ones, and it would only need to run it once for each video (if cached).
I did however test DeArrow's API and it was very straightforward. However, running it as a client-side script would essentially mean that every video would have to be checked and "DeArrowed" on the fly, and it would do that for every page refresh. That might not be very performant for you, nor DeArrow's free API service.
In short, it should be possible, but not ideal. I'm personally interested in the idea as well, but I'm not sure if I'll have time to tackle this.