It's available, you might need to search for it and look for the flow charts to see which courses are missing from the other departments.

The challenge is, in many places, you won't be able to practice as an engineer without going through an accredited program.

If you're trying to be a maker or learn more about that, mechanical engineering is probably overkill. There are more accessible books for technologists or technicians that have a much more reduced emphasis on math.

An undergrad degree in engineering isn't sufficient to be an engineer. It's the base knowledge that gets built on during the apprenticeship ("engineer in training" or other name), and you need to learn and use the relevant laws and standards.

If you're able to state your goals a little more clearly, there may be others who can provide better advice or comments.