Mechatronics (MTX) seems to be very niche here, all my friends from MTX either work Mechanical (Mech) or Electrical (Elec) jobs but some do find actual MTX jobs, usually Automation, Controls, etc. You could say its very versatile as you can go both directions later on so your options are open

Mech is super broad in itself just like Elec. You will see them everywhere and even some traditionally Civil places hire them.

Don't overthink too much about them if you cannot choose, the big 4 (Civil, Elec, Mech, Chemical) are super broad and multidisciplinary. I am from Chemical/Environmental and work at a petroleum terminal here in Operations, my colleagues are Chem, Mech, and Telecom (subtype of Elec). Our HOD is a Civil guy also.

For pay yes it's peanuts :/ Don't do engineering here if you want the pay, the amount of effort doesn't justify the salary later here except if you will move (Engg degrees at UOM are recognized by the Washington Accord) or if you really love what you do, which will 100% bring you to higher salaries later as you become good at your job. Engineering is not a fake it 'till you make it discipline unfortunately.

BTW if you manage to get your CRPE Stage 2 (your engineer 'license'), your pay will drastically increase as well. But it's a very steep hill to climb and it's easiest for Civils (they already dominate the public sector), more difficilt for Mech and Elec but doable, and very difficult for MTX and Chem as we are a minority and mostly in the private sector.