There are some misunderstandings here.
Windows 10 installs are mostly on newer computers with UEFI. If it has UEFI, it has GPT partitioning.
boot0 will not work on that at all. It can't, it doesn't know how to deal with a partition format that came along something like twenty years later. The bad thing is that having installed it now, it has overwritten some of the PMBR. It might not matter, since UEFI ignores the MBR bootcode anyway.
If the computer was an upgrade from Windows 7, it could still be using MBR, in which case
boot0cfg(8) would work.
For dual-booting with Windows 10, the UEFI firmware might allow setting up boot options. The latest Dells I've bought all have this.
Otherwise, yes, you do need Grub. See
https://forums.freebsd.org/threads/49055/.
As far as the very first post, "can't install" tells us nothing. Specifically, what did you do and what happened?