[carpdad]

If you have another choice, take another path. Lint collects in dryer duct and it must be cleaned now and then. Duct does not have to be removeable but threaded with a duct cleaning brush and to outside. If the dryer is in a kitchen, the machine removeable, duct detached, and inserting the brush. Duct also collects some moisture although that hasn't been a problem for me over the years.
Amazon has such a brush. It's 4" round and has 10' coil with a handle. Learning from a poster, I cut off the handle and thread the coil in first to outside (vent cap with a removeable screen). Then pull the brush. After a couple of passes, blow through the duct with a leaf blower. To clean with a brush, fairly rigid duct is a must. I used galvanized metal duct, no plastic flex duct.
If under the cabinet, use fairly heavy gauge sheet metal round duct, 4", and you can change to flex if must but the flex part must be detachable in future.

 

[3onthetree]

If you are following code, per International:

Termination needs to be 36" from building openings in any direction. So it can be under a high window.

It must be 4" nomimal round.

Transition ducts can not be concealed in construction.

 

[ardpub]

Yes, seems potential moisture and fire hazard.

 

[ratherbefishing]

I can't give you a plan. But I can tell you that, from experience, it needs to be easy to clean. As smooth as possible on the inside. Every protruding screw, sharp edge, or rough spot will catch lint. We're using a simple periscope duct. Smooth and slick inside, no lint. But the transition to the outside vent catches lint. Last time I cleaned it out, drying times decreased by about 33%.