I don't believe mine or Ivor Tingting's advice to be negative,cautious perhaps but don't forget the OP is 175kg and a heavy smoker.
He would need a bike that would support his weight and there aren't many about,certainly no touring bike I'm aware of,so the Elephant bike may work for him but would need to be as you say ridden on short flat rides initially until strength is gained and some weight lost.
Overall he needs to be careful and visiting his doctor would be a good initial step along with a strict diet and quitting the fags if his aim is to get fit.
You've missed my point entirely.
OP came to this forum asking for advice about a new bike, and you and Ivor took it upon yourselves to offer advice about his diet and lifestyle. Ivor went as far as suggesting he wouldn't be able to ride a bike at all, which is unlikely to be true.
Everyone needs to start somewhere. It is neither realistic nor reasonable to expect someone who has spent years or even decades gradually gaining weight to immediately about turn their entire lifestyle. If you advise people to do so, you set them up to fail, which perpetuates the (false) belief that change is impossible.
A little bit of progress every day adds up to a series of little victories. That's how you change a life.