Maybe in the modern age someone could make a "polarhome in a box" that offers a similar gamut of systems, but via preconfigured emulators that you can simply download and run.
Until now, I have used qemu (or rather qemu-system-aarch64 in combination with binfmt-misc) on Linux to emulate e.g a Raspberry pi running on arm64. This works very well, but for e.g. Solaris or HP-UX there is the extra hurdle of getting hold of bootable media that will not freak out in the unfamiliar surroundings of a qemu virtual machine.
I have never tried, and it is possible that I overestimate the difficulty...
KVM (x86 and x86_64): Linux, BSD, OSX, Hurd, Haiku, MSDOS, Minix, QNX, RTEMS, Xenix, Solaris, UnixWare, Windows 95 through 11.
QEMU (for non-x86): AIX 4, Linux (m68k, arm, sparc, powerpc, mips, riscv), OSX (ppc), Solaris 8 (sparc), SunOS 4.1.4 (sparc), Windows NT 4 (mips)
SIMH (for old DEC computers): NetBSD, VMS, Ultrix, RSX-11M, RT-11
Some of them can be quite finicky to get to work. Xenix was especially hard.
Solaris 11 is quite easy to get running in QEMU/KVM though. You can download the media from Oracle.
The only real hardware I routinely run has either Debian Linux, macOS, or Raspberry Pi.