Inflatable PFD’s are allowed as carry on luggage however it’s best to go to the TSA sight and print out the rules as many TSA agents don’t understand their own regulations.

You may bring a life vest with up to two CO2 cartridges inside, plus two spare cartridges in your carry-on or checked bag.
Even if an item is generally permitted, it may be subject to additional screening or not allowed through the checkpoint if it triggers an alarm during the screening process, appears to have been tampered with, or poses other security concerns. The final decision rests with TSA on whether to allow any items on the plane.
You may not transport CO2 cartridges without the associated lifejacket.