Hello HanPa
This HP site gives some details on your Wave PC. The first note at this site below the pic states" The chassis is not designed for hardware upgrades."
Have you opened it up to have a look see inside? I have no idea on viable upgrade options as I have never checked one of these PC's out.
There is an M.2 PCIe 3x4 socket on the board. Some of this type socket can run in SATA or PCIe mode, some are limited. An M.2 slot limited to SATA will disable the SATA port on the motherboard.
There is a 1 TB SATA HDD installed by HP. You may be able to add an M.2 drive or replace the HP HDD with a 1 TB SATA SSD.
Messing around inside of this type PC could void your warranty. You should talk to HP Support.
Grzy