One that I’d like to see is a more in-depth sorting option for posts (allowing you to see for example top of December 2020, or top of a specific day). A custom date range selection would be best. I remember this being a frequently requested feature in the early days of reddit, and they never implemented it.
Every links are opening in my browser, worth noting that I’m using Firefox, so it may be a problem of its recognition as a browser by Lemmur. You may should open an issue on their github.