I can recommend you Zettelkasten. I actually wrote software for myself, in my opinion you get the most freedom that way and second brain should be custom tailored for you.
New software that is getting praise right now is Roam Research, but I haven’t used it
Pretty much like paper in the end, but without paper.
It also has the advantage that when you add screenshots, those are also OCRed and searchable.
It's not quite as native feeling as grabbing a pen and paper though, so it takes some getting used to.
So I can write notes using vim. I have a lot of shortcuts so its raster than clicking around in Archiver.
I also have integratation with Anki, so I can add flashcards from the program into long term memory, and have it structured in a way