Btw, I figured out how to think about this:
Mojo is a strict superset of Python, while LPython is a strict subset of Python.
With all the pros and cons that follow from this: Since any LPython code is just Python, you can use the existing Python tools with it (and it runs with CPython). But you need to modify your existing Python code to use with LPython (although we give you very nice messages), and in return you get Fortran speed. Mojo is the complementary approach: any Python code is Mojo code, so you don’t need to modify your code, although it won’t run at top speed, for that you must gradually modify it as well.
Finally, LFortran is a strict superset of Fortran. So any Fortran code will work with LFortran (eventually, once we enter production). But you shouldn’t need to modify your existing Fortran code to run fast with LFortran (this is different from Python, since Python by default is not fast, while Fortran was designed to be fast).