Don't do it. That bike was not designed for it and you will screw up the whole geometry of the bike which will throw a lot of things off in a bad way. Plus you would void the warranty which you may not have anyway but still. If you are really desperate for more comfort try to fit wider more supple tires run them at lower pressures, find a compatible carbon fork (which will be expensive and not worth it on a heavily Tourney equipped bike) and look at things like the Kinekt seatpost or stem or Redshift ShockStop Stem (however not both stem and seatpost as it will lead to poor fit and really odd riding).

Also I would not even if the bike were suspension ready look at used stuff if you are so unsure because you could be dealing with a lot of sellers who are also unsure and that could lead to a ton of expensive mistakes. The only time I really want a suspension fork is if I am mountain biking or riding generally at higher speeds on a heavy e-bike. I don't want the weight or the energy lose on the road

In the future I would look at a good steel frame or titanium frame which will help smooth out roads. Aluminum on aluminum tends to lead to a stiffer ride and more transfer of vibrations to the rider. Carbon can also be nice depending on how it was constructed some bikes are designed to be super stiff and others designed with a bit of compliance however steel and titanium will generally last forever and some steel can be a little less costly plus I can mount racks and such to steel and titanium whereas with carbon not so much generally.
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