Perhaps there are millions of RF power amplifiers from China that have the same performances as similar ones from any part of the world, and the only difference is the price. This is a fact, and not an amateur radio story.
If don't have experience designing and manufacturing and evaluating a high power RF amplifier (as ITP mentioned), the PA will not die in few seconds, but will die in few milli-seconds.
If you burn a $200 MMRF1308HR5 transistor bought from NXP you get nothing, but AliExpress give total refund in less than a week for products that doesn't work when you receive them, so the risk losing money is minimum.
And when you get a PA with 300W on 50 ohms, you can start thinking what to add at the output (isolator, circulator, tuner, etc.) to get the desired performances.