If I was in charge of Microsoft or Apple, I'd look into one of those OSes to fund and exchange code with instead of creating one from scratch.
While they are not ready for prime time if some billion dollar company invests one million USD in just one of them, it could get it to get out of the alpha stage and go beta or retail in a few years or so.
Haiku is an open source free rewrite of BeOS and they are trying to make an OS that can run BeOS apps. https://www.haiku-os.org/
AROS is an open source and free AmigaOS 3.X rewrite, it can run old Amiga apps.
http://aros.sourceforge.net/
OSFree is an open source and free OS/2 clone. http://www.osfree.org/
ReactOS is an open source and free OS to try and be like XP/2003 in a way and has made some progress recently.
https://reactos.org/
If I was in charge of Microsoft or Apple, I'd look into one of those OSes to fund and exchange code with instead of creating one from scratch.
While they are not ready for prime time if some billion dollar company invests one million USD in just one of them, it could get it to get out of the alpha stage and go beta or retail in a few years or so.