In general they just need _something_. If Windows Hello has even a pin number, Chrome and FF webauthn prompts will use Windows Hello as a TPM provider (assuming

In general they just need _something_. If Windows Hello has even a pin number, Chrome and FF webauthn prompts will use Windows Hello as a TPM provider (assuming the website is using actual Webauthn and not the older U2F-compatible standard, which some sites still use for compatibility, eg google). If they don't have anything, then they will definitely need at least a usb hardware key.