Property and equipment, net - Composition (Details) - USD ($)	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Gross property and equipment, net	$ 6,864,203	$ 4,688,604
Less: accumulated depreciation	(3,311,647)	(2,778,113)
Prepayment for purchase of equipment and construction-in-progress	81,784	0
Total	3,634,340	1,910,491
Building
Property, Plant and Equipment [Line Items]
Gross property and equipment, net	946,066	946,066
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Gross property and equipment, net	1,919,687	1,695,361
Machinery and equipment
Property, Plant and Equipment [Line Items]
Gross property and equipment, net	3,549,167	1,613,439
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Gross property and equipment, net	274,994	259,449
Vehicles
Property, Plant and Equipment [Line Items]
Gross property and equipment, net	147,912	147,912
Molds
Property, Plant and Equipment [Line Items]
Gross property and equipment, net	$ 26,377	$ 26,377