I think openCV is already part of the stabilizer filter and it looks like RIFE just based on that.
Maybe it’s not a huge effort to implement it as a filter or in the streamline before handing frames over to ffmpeg.
Currently i use it standalone to convert some clips to higher framerates.
And maybe i’m not the only one who put clips of various framerates (24,25,30,50 and 60 FPS) into the timeline and got stuttering results.