About 1 year ago @anton told us they have no plans to add tabs, see quote below:
See full post here: Development pace (roadmap for 2025?) - #16 by anton
Sadly, as far as I know that splitscreen and multi column navigation was not added in 2024.
There has been another post by either anton or another member of the team explaining a bit more what splitscreen would be and if I remember correctly it would be something like Logseq. Where you can open pages in a sidepanel but I cannot find this post sadly so take this with a grain of salt please.