Yes I understand Apple doesn't want people getting into these computers, but I'm wondering if it is possible or if, like the RAM, the SDD is somehow soldered on like many of the other components?
The SSD is a proprietary one. There are a number of manufactures now making the form-factor and connector (the new form-factor called M.2 if you're curious), but since Apple uses their own design, these other options won't work. Perhaps a manufacturer like OWC will put out alternatives for those of use who want to upgrade.