PCem is described as 'offers emulation of various IBM PC compatible machines, from the original 1981 model 5150 to later successors and clones by third party manufacturers'. There are six alternatives to PCem for a variety of platforms, including Mac, Windows, Linux, iPhone and BSD. The best alternative is VirtualBox, which is both free and Open Source. Other great apps like PCem are UTM (Free, Open Source), Multipass (Free, Open Source), 86Box (Free, Open Source) and pcemu (Free).
Multipass is a lightweight VM manager for Linux, Windows and macOS. It's designed for developers who want a fresh Ubuntu environment with a single command. It uses KVM on Linux, Hyper-V on Windows and HyperKit on macOS to run the VM with minimal overhead.
86Box is a hypervisor and IBM PC system emulator that specializes in running old operating systems and software designed for IBM PC systems and compatibles from 1981 through fairly recent system designs based on the PCI bus.
Here you can find the original version of David Hedley's 8086 PC emulator, and my "improved" version. This will emulate a basic PC with a VGA text-only display quite well; there is a reasonable amount of software that will work with no problems.