Pistols always sound a good idea, but carried as a secondary is just weight
You can reload pod to hopper quicker - and for anything other than that you are planning to fail rather than maintaining & learning to keep your main ready
But they are fun
You have general choices :
Common cheaper pistols - but tend to be chunky like the delta 68 etc (basically a spyder chopped down)
Alternate sized pistols such as .43 or .50 calibre
If willing to pay the money then there are the TiPx and Tiberius, but as a secondary that's a lot of money on a pistol that you intend to carry and not use
There are a few threads on reasoning and their advantages.
If just as a secondary sidearm then the TiPx can be carried with a 12 gram unpunctured until you fire. (In theory take it to every game and don't use any 12 grams if you don't shoot - however you need to chrono which means you use at least one per day )