A part of my shack is a 50 Ohm dummyload from Aliexpress which can be ordered from this shop.
This is how the Dummyload behaves between 2MHz and 6.3GHz. The measurement was done using a calibrated LiteVNA-64.
I tested the capability to burn 10 Watt by transmitting a constant CW signal for several minutes. It didn’t went up in flames.
For further Investigation you can have a look at the S1P files:
This files can be investigated using NanoVNASaver.