Neither item currently has a source, and the appearances of both are encrypted, so we can't see what they look like. However, it's highly likely that these two exteriors are linked to the cozy cabin decor recently datamined in a prior 12.1.7 build.
That decor is listed with the In-Game shop as a source, and players have been very vocal regarding their desire to be able to earn these new customizations in-game. It's possible that the Cozy and Icy cabins are also related to an upcoming shop pack, but it's equally possible that these could become available from the same neighborhood vendors that sell the Autumnal Westfall Barn Facade Plans and Springtime Westfall Barn Facade Plans exteriors.
