No, it is not possible to install two NVMe SSDs in this PC. This model has a single M.2 2280 slot for NVMe SSDs, as indicated in Dell's official documentation for replacing the M.2 2280 SSD.
In addition, although BIOS changes allow an NVMe SSD to be used as a boot on this type of machine, this relates to a single NVMe slot via a PCIe adapter, not two NVMe SSDs simultaneously.