Ever since ‘m’ got remapped to ‘shift-m’, I’ve been realising that the go-to-oldest-unread key has always been a bit of an outlier for how I nav the site.
95% of my reading, I use the up/dn arrow keys to hop from story to story. When I finish off a feed, I use shift-up or shift-dn to go to the next feed.
If we could map ctrl-up/ctrl-dn or alt-up/alt-dn or something like that to mean “go to topmost/bottommost unread”, I could do pretty much 100% of my nav via the arrow keys! This would be incredibly fast (and probably very intuitive).