You have probably heard about “burner phones“. An “app version” is Hushed Phone which was posted earlier. If you don’t want any linkage to your real identity, these are ones bought with cash, with prepaid minutes, and meant to be disposed of to eliminate traces of your communications. For those situations you don’t want traced back to you, say after you blow the whistle on your company and you don’t want to be associated with that phone number.
Burner cards are one-time use credit cards for purchases where you don’t necessarily trust the other party, perhaps an overseas purchase, and you don’t want to give out your real credit card number. Sure you can use PayPal too, and cash is king for local craigslist purchases.
https://privacy.com/ claims to be free to use, and you do have to trust them with access to your bank account. Read the FAQ and details, and “caveat emptor”.
Note: I have not tried this personally.