When looking through aircraft engine specifications, turbofans always provide a thrust value, e.g. in JT8D engine: https://prattwhitney.com/products-and-services/products/commercial-engines/jt8d
In constrast, turboprops do not provide this value, see PT6A engine page: https://www.pwc.ca/en/products-and-services/products/general-aviation-engines/pt6a
Why is this the case?
Because the turbofan's thrust value is derived from the integrated fan unit that is part of the engine. It's all an integrated product of the engine manufacturer.
A turboprop's thrust making component, the propeller, is a separate item completely, and the thrust the propeller can produce, for a given input torque and RPM, will vary from propeller design to propeller design, there being numerous variables within different propeller configurations.
If P&W built the PT6 with a specific propeller with specific characteristics, and that was the ONLY propeller that could be used, then P&W could provide a thrust specification for that engine/propeller. But since they don't make the propeller, they only specify what they can specify for the engine itself independent of the prop, which is the engine's torque and horsepower.
It's a bit of a historical reason. In the olden days of only piston engines powering aeroplanes, the unit of measurement for the capability of the engine was the Brake Horse Power BHP. The engine powers the propeller, and with data on propeller blades and airspeed the resisting torque can be determined - the determining equations are of a rotary and variable nature, like those powering the tyres of an automobile.
When the first jet engines were designed around WW2 like the Junkers Jumo above, there was no external device to power up. Enabling the aeroplane to fly was a stream of exhaust gases, which provided thrust in an amount that was relatively constant over airspeed. So turbojet capability was expressed in kgf, lbs or whichever olden days unit, now kN of course. Much more convenient for computing aeroplane speed.
Nowadays most larger aircraft are powered by turbine engines. When they power a propeller or helicopter rotor, it still makes sense to consider the rotary output shaft power as one of the inputs for the thrust equations. Propeller tip speed, number of blades, airspeed, blade angle would be some other inputs, with constant speed propellers adjusting the blade angle automatically to provide optimum thrust from the available power.
When the turbine powers a fan there is still a propelling stream of exhaust gases generated by the engine, but the situation is not as clear as in case of the turbojet. Graph above is from prof. Wittenberg's TU Delft book VTH-D 14, and plots the thrust ratio over speed for various bypass ratios $\lambda$. The pure turbojet of $\lambda$ = 0 is indeed relatively constant over airspeed, higher bypass ratios are not. Turbofan thrust is a variable of airspeed, like propeller thrust is.
So would it make sense to express the turbofan potency in kW, since the fan looks a lot like a propeller? For two reasons it does not:
In order to compute the aircraft speed/altitude capabilities we need the available thrust. Turbofan power is still expressed in kN despite the variability over airspeed, turboprop power in kW shaft output despite the constant speed implementation - a historical reason.
