I've had snapdragons overwinter. I don't remember any making it through two winters, and I don't remember the variety.

I've not ever seen them grown that way in my zone. That said, like mad_gallica alluded to, annual may overwinter in any given winter. It's a crapshoot, though.

At a former house, i grew rocket snaps along the drive beside the house, which was made of stone and south facing. I don’t recall how long they lasted but at least a few years. That house was considered z5 at the time, but it was a pretty specific microclimate.

I'm in 6A in Indiana and had snaps in both my in ground cutting garden and some in pots on the front steps overwinter and bloom like crazy in 2024. Probably won't happen this season with the arctic blasts last week! But I'm not pulling them in the fall anymore.

I've regularly had snaps come back for 2-3 years. 6b, microclimate pockets. Keep in mind that they are short lived, usually 3-4 years at most. But they are also self-sowers, so if you can get your snaps going, you might not notice which is a 3 year old plant next to a first year plant.