BALANCE SHEET COMPONENTS - Schedule of property and equipment, net (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ (1,171)	$ (2,242)
Total property, plant and equipment, net	410	407
Depreciable Property, Plant And Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,581	2,577
Total property, plant and equipment, net	410	335
Research and development equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,291	1,826
Office and computer equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	84	494
Autos
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	54	54
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	47	46
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	105	157
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 0	$ 72