There ie the rockchip CM3588 NAS Kit but it is a non mainstream CPU which cost between 200-300€:

https://wiki.friendlyelec.com/wiki/index.php/CM3588_NAS_Kit

there is also the asustor nas: https://www.asustor.com/de/product?p_id=80

If you just need a single nvme SSD you could also buy a banana pi 3 Router:

https://wiki.banana-pi.org/Banana_Pi_BPI-R3

Edit: forgot links and product