Which SMRs don't have a full scale containment vessel?
None, although I think some (NuScale?) save money by sharing pressurized containment volume among multiple reactors. Just hope you don't see multiple correlated meltdowns.
Containment vessels could also be made smaller if steam filtering were used instead of planning to just contain and condense it. I don't know if any SMRs plan to do this.
NuScale's containment vessel is a metal cylinder around the reactor.[1] Each reactor has its own containment vessel. It's just slightly larger than the reactor, like Fukushima and Peach Bottom. Here's a good drawing.[2] No user-serviceable parts inside.
The building is not a containment.
[1] https://www.nrc.gov/docs/ML1535/ML15355A411.pdf
[2] https://spectrum.ieee.org/media-library/image.jpg?id=2557419...
As other poster mentioned, each nuscale module is fully self contained. Not only that, but they've modeled every module having a simultaneous scram in a 12 module plant, and modeled that the water level was lower than nominal. Still walk away safe.
Some of the "small modular nuclear reactor designs are built on the assumption that they don't need a full scale containment vessel because nothing can go that wrong. That may not be a good assumption. There's a lot to be said for large amounts of steel and concrete around reactors.