If you run an open source hardware project like we do with our DIY air quality monitors [1] you can also monetize it via selling hardware kits or work with affiliate links to e.g. Amazon or AliExpress.

However selling hardware has some additional challenges e.g. warranty, lost shippings, component shortages etc that you need to factor in.

[1] https://www.airgradient.com/open-airgradient/kits/