That's a good idea btw - here are some of the most-favorited comments from this past week:

https://news.ycombinator.com/item?id=47258500

https://news.ycombinator.com/item?id=47238442

https://news.ycombinator.com/item?id=47237467

https://news.ycombinator.com/item?id=47232961

https://news.ycombinator.com/item?id=47226535

https://news.ycombinator.com/item?id=47214629

https://news.ycombinator.com/item?id=47210627

https://news.ycombinator.com/item?id=47206393

Only a couple of those were already in /highlights.

I'm not sure yet whether this is good enough to be an automatic feed into /highlights but I could imagine adding aggregated /favorites pages to https://news.ycombinator.com/lists.