The Ruger SA's use different cylinders, for each different caliber. There is a reason for that. The main reason is the difference in the size of the cases.
In .45acp / .45 Colt the dimensions are very close, but not identical. Specs call for the .45 Colt to be .480" from case head to mouth. The .45acp is .476" at the case head, and .473" at the mouth.
The .357Mag is .379" at the head and mouth, the 9mm Luger is .391" at the head and .380" at the mouth.
Swapping cylinders on a Ruger SA is simple. Fitting them is simpler than doing so on a DA. I'm sure multiple cylinders could be fitted to a DA revolver, BUT, no factory I know does this. Probably due to the additional costs & complexity of fitting, vs market demand.
The clearances needed for moon clips add to the cost of fitting the DA cylinder as well. Think about the typical DA revolver, and swapping cylinders. With an SA, you only swap the cylinder. Pull the base pin, cylinder drops out, put in the other one, replace the base pin. Simple.
With a DA cylinder, you have to get it off the crane, and you have the extractor assy to deal with. No one is interested in having to swap the extractor assy between cylinders, (and the potential for damage if done regularly by the user is very high), so to make a DA practical with an additional cylinder, you need the entire assembly to swap out. This makes for much more complex fitting of the cylinder and costs go way up.
And, this is separate from the clearance issues needed to run moon clips. It can be done, but is not done outside of commissioned custom work, simply because the market will not support the cost.
Essentially, the auto pistol rounds don't fit the revolver round's chambers (.45acp is slightly too small, and 9mm is too large), so shooting them in the same chambers is a non starter, even with moon clips to headspace from. SO, one cylinder just won't do it.
And two cylinders while fairly simple in an SA becomes much more complex in a DA. Too complex to be viable on the market.