Learning these OS can have other, peripheral benefits

Very true. For reference, Solaris has been more or less dead ever since Oracle killed Sun and re-closed it. Now it's officially dead beyond "support" contracts, subject only to any benevolent and heroic zombie efforts, which are extremely unlikely due to its [line]age and license... https://meshedinsights.com/2017/09/03/oracle-finally-killed-sun/ Still, it presents a different attack surface, at least beyond the network application itself, if you can compile on it. Run a few nodes for fun if you want (fun being half the point of running nodes), you can still get the i386/amd64 binaries here... https://www.oracle.com/solaris/solaris11/index.html But as a formal production OS, especially for the non-corporate opensource community since ever, Solaris proper is deader than long decayed and untouchable dead. If you want the Sun family lineage, go with https://www.openindiana.org/ or maybe if you're stuck in the GNU toolchain, https://www.osdyson.org/ or if you want something that's actively maintained with at least some actual "Unix" heritage and unique feel https://www.freebsd.org/ or any other BSD like Open or Dragon or Net. Every Linux / Windows / Apple user owes it to themselves to try something in the BSD family for at least a few months or so. Don't forget Plan9, Open/Free VMS, MINIX, GNU HURD, HP-UX, AIX, FreeDOS, Android, iOS, OSX, etc. Regardless of which overlay network you're using, or plugging nodes into, have fun gettin jiggy wit it :) https://www.youtube.com/watch?v=3JcmQONgXJM