Methods and apparatus to operate a gas turbine engine with hydrogen gas are disclosed. An example combustor nozzle apparatus of a gas turbine engine includes a first circuit to transport a blend of hydrogen gas, inert gas, and/or other combustible gas from a supply to a gas turbine combustor, the blend of hydrogen gas, inert gas, and/or other combustible gas including between 100% hydrogen gas, 100% inert gas, or 100% other combustible gas, a second circuit to transport water from the supply to the gas turbine combustor, and a nozzle tip. The nozzle tip includes a first outlet in connection with the second circuit to provide the water to the gas turbine combustor, and a second outlet in connection with the first circuit, the second outlet concentrically positioned within the first outlet to provide the blend of hydrogen gas, inert gas, and/or other combustible gas to the gas turbine combustor.