How to create system users on Androidx86?

I am trying to create system users on an Android x86 virtual machine, but the binaries adduser and addgroup don't exist (neither useradd or usermod). I installed BusyBox to get access to these utilities but when trying to run addgroup to create a new system group I get error addgroup: /etc/group: No such file or directory. When trying to run adduser with an existing system group I get error adduser: unknown group net_bt_admin. The only way to create users I found so far is through pm create-user, but these are android level users, how can I create users quivalent to shell or system default users?