It isn’t currently possible within Obsidian, though you may be able to make some automations that help compile these things for you. E.g., a script that compiles all such [[TODO]] lines in your file every 15 minutes or something.
There has been talk of transcludable searches, which would resolve this issue, I think. E.g., a search query returns all lines that have [[TODO]], and you just display the results of that search in the note.
Otherwise the idea you’ve described sounds like it would make for a good plugin!