JEYI NVMe M.2 to 5 Sata Adapter.  https://smile.amazon.com/Adapter-Internal-Non-RAID-Desktop-Support/dp/B09N8MCDTZ/

I'm building a new unraid server because my motherboard finally bit the dust.  I was going to buy a 300+ motherboard with 10 Sata ports but found this item below which can plug into an m.2. slot and give you 5 more drives.  The potential is awesome.  I imagine that you could have 4 of these on a system and have 20 drives.  i.e. two in two m.2. sockets and two more of these in a pcie x16 to 2 m.2 https://smile.amazon.com/SilverStone-Technology-Advanced-Solution-ECM22/dp/B075ZNWS9Y/

 

Specs.

1. M.2 Key M SATA3.0 expansion card, using the latest JMB585 chip solution, high-speed transmission and stable performance, in line with M.2 Key M standard

2. Realize the PCI Express Gen 3x2 line bandwidth, with five SATA ports extending from the PC host to the M.2 Key M slot, the transmission speed of each port is up to 6Gbps

3. Transmission protocol: PCIe x2, PCI Express supporting up to two channels

4. Support PCI Express link layer energy saving mode

5. Support command-based and FIS-based port multiplier

6. Support AHCI mode and IDE programming interface

7. Support local command queue (NCQ)

8. Support SATA plug-in detection function

9. Support drive power control and interleaved rotation

10. Support SATA Partial / Slumber power management status

11. Complies with PCI Express Basic Specification Revision 3.1a, SATA Specification Revision 3.2

12. Plug and play, no other software installation or setting required

Specification:

Name: M.2 Key M SATA3.0 expansion card

Chip set: JMB585

Transmission protocol: PCIe x2

Media interface: 5 x SATA 3.0

Transmission rate: 6 Gbps

Management functions: SATA plug-in detection, SATA Link power saving mode (partial and hibernation)

Operating system: Linux, Win 7 / Win 8 / Win 8.1 / win 10, 32 & 64bit

Size: 80 * 22mm