As of now, it’s impossible to individually select text across blocks without activating the block selector. We should be able to select text across different blocks without selecting the entire blocks themselves. The way this functionality is currently achieved in apps like Notion and Heptabase is that the selection element only appears when activated from the margin. This way, characters can easily be individually selected from within the editing section, while the option for whole block selection still remains.
When Notion made this evolution, it was so positive!