It’s possible, but you have to be prepared for a foamy, messy volcano of beer. See, when you introduce dry hops to carbonated beer, you also introduce a catalyst that causes CO2 to be rapidly released. This can result in violent foaming. If you want to dry hop pressurized beer, be sure to depressurize the fermenter first. Keep the lid nearby. Or, you can purchase the FermZilla fermenter that has a dry hop port.