no disk to install os

If your laptop already had macOS 10.13+ installed before your original Apple SSD failed, then you just need to boot from a macOS 10.13+ installer either from a bootable macOS USB installer or from Internet Recovery Mode (Command + Option + R). Unfortunately Internet Recovery Mode won't always boot the most recent macOS installer using that key combination.

If macOS 10.13+ was never installed on this laptop prior to the Apple SSD failing, then unfortunately you need to have an Apple original PCIe SSD installed internally in this laptop because the system firmware updater requires this exact hardware configuration. In addition you need the proper Apple PCIe SSD for this exact model laptop since macOS knows which SSD belongs in some laptops. I have personally seen macOS refuse to boot or install when the wrong Apple PCIe SSD is installed in a Retina laptop even though a non-Apple OS will work perfectly fine. Apple has made a real mess of these Retina laptops and macOS.

You must actually install macOS 10.13+ and not just boot macOS externally in order to install the system firmware update. Even if you want to install macOS 10.13+ to an external drive you must first have an original Apple PCIe SSD installed internally and the internal Apple PCIe SSD must be properly partitioned & formatted.

Without the system firmware update from macOS 10.13+, then booting from an external macOS 10.13+ USB drive won't see the NVMe SSD.

In order to use an NVMe SSD requires using macOS 10.13+.

Using an NVMe SSD also requires that the laptop's system firmware was first updated to support an NVMe SSD before installing the NVMe SSD which means that you had to have had macOS 10.13+ already installed on this laptop before replacing the original Apple SSD.