I wonder if there is an (easy) way to add checkboxes inline, horizontally rather than on separate lines? That would be really cool to do “down & dity” simple task tracking.
Not very easy, no. You could probably make a CSS snippet that would make all task lists horizontal, or narrow it by class and add a class to pages where you wanted horizontal task lists (all task lists on those pages would be horizontal).
Or you could try using HTML checkboxes (a template would make it easier). I don’t know if those work the same way in Obsidian.