None.
X-Plane comes close to FlightGear. It has far-superior visuals. fully functional glass cockpits like the Garmin G1000, and simulated ATC, but the vast array of community-made planes available in FlightGear still kinda seals it for me, despite the jank.
FreeCAD has its pain points. Software like Creo Parametric is much more robust in a lot of ways, but I literally cannot run it on Linux (no mouse-wheel zoom in WINE, slide show in QEMU). Fundamentally, they are similar enough, and my work primarily takes place on a component level so I can live without the streamlined assembly workflow. Also, FreeCAD doesn’t cost >$2000, and can still do FEM analysis and computational fluid dynamics. Maybe I could find a crack for SolidWorks and try that out, but it takes a long ass time to learn a CAD system proficiently.
Everyone who learned on Photoshop says the GIMP interface is weird, but I learned on GIMP and can say the same for Photoshop.
Games are the only exception, but games aren’t fungible. Minecraft is not a substitute for Dwarf Fortress. CS:GO is not a substitute for Unreal Tournament.
The war would end, a whole lot of people would stop getting killed, and it would open a sliver of space to organize on class lines instead of nationalist ones.
As it is, it is basically illegal to be a communist or an anarchist in Ukraine, and the country is under martial law with NATO-armed and trained fascist brigades doling out summary justice. Could it get worse? Why should the left advocate for people to die on the hill of a country which arrests communists, dismantles labor unions, and liquidates public infrastructure on internet auctions for foreign investors?
If you take the most vulgar Anarchist approach, all states are bad, full stop. Political practice doesn’t even operate on that paradigm. You struggle to undermine oppressive hierarchical systems that you come in direct contact with through direct action. If you take the vulgar Leninist approach, the Proletariat should struggle for the overthrow of their Bourgeoisie (this would include the proletariat of Ukraine and Russia respectively, as well as the proletariat of Western countries which see this conflict only as a means to strengthen their military alliances and diplomatic positions). Of course, the situation is too nuanced to apply such a vulgar approach, but that should be the STARTING POINT for anybody who considers themselves anti-capitalists. You should be able to justify any deviation from those bedrock positions.