According to the PCem project website, its lead developer, Sarah Walker, has recently decided to quit active maintenance:
This is unfortunate. PCem has a much wider range of legacy graphics and sound cards than QEMU for more resource-intensive objects: games, animation, multimedia art, etc, as I believe @Cynde_Moya has investigated. Hopefully active development will pick up again from someone else, though it also looks like there is a previously-existing (Windows-only) fork at https://86box.net/