ReactOS was started somehow in 1996 (and still in alpha?), Haiku-OS is in beta 5 (initial release was in 2002 per Wikipedia) and Microsoft required years for creating Chicago/Windows 95 or Longhorn/Vista

How many years do you need to create own OS? Is it even possible?

PLLinux is mainly merging existing software and after four months there is quite useable text/console environment ready (with building ISO, installing system into new partition, app package manager, configurator and many other things). System in this moment is going with quite big steps into TP (Technology Preview) release.

But how even it is possible? Anw why many organizations need many people and money?

I will try to answer on first question:

• text/console environment is quite easy
• architecture implemented inside PLLinux is extremly modular (which makes work very fast)
• changes to existing apps are marginal (two exceptions: some extra features need cosmetic update in bubblewrap + dynamic loader needs knowledge about PLLinux manifest files)
• project tries to get away from politics and is concentrating just on real work (where the most important is technical excellence and results)

With this approach TP could be possible this year and full graphic environment maybe next year. No bla, bla.

And please note, that majority tasks are done on small mini PC. Laptop could be enough too. And no AI is required.

(you could say in this moment, that it will be always worse than things done by big companies with many employees and partially it will be the truth, from the other hand please check, how big and unnecessary effort is put by them into making some patches or other stuff just because architecture is overloaded and ineffective and cannot be changed because of agreements or because people want to make their work without end)