My opinion is that sadly in 2020, most local governments will make it very difficult for you to comply with the building rules if your goal is a house that is anything different from what a "normal" house is.

Like the other commenter suggested, try with a shed, or even better, try making a tabletop model of your cabin with all the measurements and cutting scaled down from your ultimate goal.

If you do find a place to build, then great! But most likely it would be occuring in an area so far outside of town that it would be a very different life from suburb living.

Though I do know of a few people who made a house within a house....

ever built anything? done a major remodel? practice first by building a shed in your backyard. you don’t want your cabin to be your first rodeo.

most important is learning to hire quality subs. very very hard if you’re not a GC in the biz.