I was told to type ? for available keyboard shortcuts.
It tells that typing b does Bookmark post.
However, it seems to not do the same as clicking on show more then on bookmark this post.
Instead, it seems to bookmark topics, instead of posts, like the Bookmark button at the end.
I believe you have to select the post first using j or k to navigate up and down. You’ll see a vertical red line on the selected post. Then you can press b to bookmark the post.
Curious that it don’t use the position set with the mouse, which we find in the URL. But maybe this is a design that keyboard shortcut users are accustomed to.
Or maybe it’s remaining bugs: I got errors like “Cannot bookmark the same post twice”, often when using both the keyboard shortcuts and the bookmark buttons, but also when I type b twice in a row.