As an "infinite grid", there is https://strlen.com/treesheets/, but it is not exactly geared toward your aim (more like a spreadsheet/outliner combo, or "hierarchical spreadsheet").
Maybe I shouldn't have mentioned a Microsoft product, since I like Unix more. I just thought the problem is understood more easily that way.
Treesheets seems quite nice. Maybe I'll try it out, but I'm still hoping to find a cleaner alternative.
I tend to use Obsidian these days along with the excalidraw plugin (if you just want to try excalidraw without installing Obsidian: https://excalidraw.com/)
Obsidian is probably a nice tool, but I'd like to have my rigid grid. Graphs are ok, but I don't like how inexact they are.
I'd like just to type, and click switching between cells.
I guess it is very hard to not encounter fantasy in daily life (though most of it is marketed as reality).