Also search a lot and only found one :
The Belkin 4-Port Mini USB-C Hub with Two USB-C
All four ports support only USB 3.0 speed (5 Gbps = 300 MB/sec effective).
However please note:
The USB-C 4-Port Mini Hub does not support pass-through charging and
video output to monitor. This hub is only intended to use with USB-A
and USB-C peripherals.
Found a 2nd one from Sitecom:
Turn your USB-C port into 3 ultrafast USB-C ports and 1 USB-C Power
- USB 3.1 Type-C input
- 3 x USB 3.1 Type-C Output (10Gbps data and 7.5W power)
- 1 x USB Type-C Power Delivery (100W power)
- Supports USB SuperSpeed 10Gbps, downwards compatible with USB 3.0 / 2.0
- Supports USB Battery Charging (BC) 1.2 up to 7.5W (5V / 1.5A)