One nice thing about modulars is you can do just about anything you want.
You can have any pitch you want. You can add the garage on site and do any kind of addition you wish. Once the house is complete you can be sure the house will not be able to be seen as a moduler. Mine has a split roof which means the center part of the roof is raised and I have a covered front porch on my ranch.

Just up the road is a new cape. They added a garage and a bonus room above it too. The house is built by the manufacturer. The garage and bonus room are built by the dealer or contractor on site.

In the next town is a colonial modular that looks just like the other homes in the area. And the "other" homes were built in the late 1700s. Complete with hip roofs and porticos. And if you drove by, you couldn't tell which one is the modular.

Long gone are the two box modulars that look like manufactured homes.

check with your insurance! We were told by State Farm & Allstate our policy would be void if we did any changes to the outside. Roof line, brick, additions etc. We are very upset about this. We also bought a new one and were told by the dealer it would be like insuring a house instead of a mobile home. In Tennesse that is not the case. it is the same as a mobile home.

A modular is different than a manufactured home. A modular is as you say, a "house" and not a mobile home. It's permanent, not meant to be moved as there's no frame underneath. So all additions would also be permanent. Just like a regular house.

So of course you would have to have different insurance.