If you do not register with your real data, it cannot be resold, stolen or spied on.
Question whether individual providers really need your real data. Make up false data or provide inaccurate information if you believe that the data is not absolutely necessary for the function. Make a note of the data you have made up in your password manager. In case you do need them, you'll have them quickly to hand.
Example: You have installed the discount app of a local store. This app asks for your name, address and date of birth. Does the app really need this data? After all, it doesn't send you any mail. The approximate date of birth would also be sufficient. The app will probably also work for you with incorrect or similar data.
In some cases, you may be violating the operator's terms and conditions, but this is usually not a criminal offense. You only risk having your account blocked, but this is rather unlikely.
*Caution! Never use the data of other real people! Do not use any fake data if identification of your person is required by law or contract. For example, because a retailer would otherwise pay for shipping to a wrong address. Otherwise you may have to reckon with legal consequences.