Possible to use Azure Synapse Analytics to extract all Azure Active Directory users?

According to the Microsoft documentation,not only email information,there are many other information such as address book contacts, calendar events, user information, mailbox settings, and so on.

So you can get user information which contains aboutMe,companyName,etc. when you choose BasicDataSet_v0.User_v1 in dataset.(All properties you can get,please refer to this documentation)

By the way,your tenant admin need to opt-in to Microsoft Graph data connect if you do this.And there is no AAD connector.

Possible to use Data Factory to extract all Azure Active Directory users?

You can even use Web activity to get that data from REST API (Graph API)