Contrary to many people's perception, Iran may be more advanced than Russia and China in producing heavy duty industrial gas turbines. There was the time of good relationship between Iran and the west before the revolution. During that time Iran acquired licences to produce E class gas turbine. The gas turbine in this news is an improved version of Siemens turbine.
China and Russia may be in the top tier in indigenous design and produce military engines, but they did not have the time in working on heavy duty industrial turbines. China only reached E, F and H class from 2020s. Russia is even behind China.
If China can first produce a copy then improve on imported design such as Soviet jet engines, I don't see why Iranian can not do the same. The key is the why (it is designed in a certain way) and the hardware to produce, the rest is simple. The Iranian got both from Siemens. Essentially the Iranian GT is like a Mercedes produced in a Chinese factory, should not be a surprise.
In my opinion, Russia engaged Iran to reproduce a particular model of a Siemens gas turbine. I'm guessing because alot of the O&G equipment in Russia right now are using Siemens equipment. So it's actually better to put a Siemens gas turbine, or a copy of it into a Siemens-designed facility. It'll mate better with Siemens control system, sensors, etc.
If Russia wanted to replace their Siemens gas turbine with Saturn turbines, I'm sure that Saturn will be able to develop a suitable gas turbine with abit of time. The main reason that Russia didn't do that, was that it is much more cost efficient to replace like for like equipment in the short term.
Russia and China already have the technology to manufacture high power industrial gas turbines. If they wanted to, they could do it soon. But for now, imports are far more cost effective. China can still import Siemens and GE gas turbines for civilian use. And Russia can still engage Iran and Siemens (via grey imports and proxies) to get those gas turbines.
But let's not take anything away from Iran. To be able to reproduce a high end Siemens gas turbine under massive sanctions is a great feat. Not many peers of Iran can boast such an achievement. Even Superpowa India still can't produce it's own high power gas turbines on it's own.