The “to-do” tab isn't really the to-do area at all.
Instead, it brings up the sidebar menu that you see on desktop.
For this reason, it should be a sidebar menu on Android as well.
The benefit of this is this would also open up another tab spot in the bottom row where you could put something else.
If you made it a hamburger menu instead, not only would it more align with the desktop version, but it would also make more sense to what the button actually does, and it would give us more space to work with.
It would also be accessible from anywhere on any screen, making navigation faster.