Can I send a WhatsApp broadcast from my laptop or WhatsApp Web?

Not with a broadcast list. WhatsApp says broadcast lists are not supported on Windows, Mac or Web. You make and send them from the phone.

• A linked device, such as WhatsApp Web, cannot create or view broadcast lists.
• You can link up to four devices and one phone at a time to a Business account.
• Other things linked devices cannot do: share live location, and add or delete status.
• For sending offers without the phone, use a system that sends from the API.