you could checkout tutanota. its less of a private redirect and more just a “normal” web mail service, but it allows you to create accounts with no fuss, where other webmail providers require some kind of secondary email / phone verification.
The free tier is well… free… but they ask you limit yourself to one account (but theres no real enforcement). If you do make multiple accounts, consider throwing some $$ their way, its a cool project. They support anonymous crypto donations as well.
I use one as a spam email, and another as a seconday alias for when dealing with vendors and stuff that i don’t want filling up my primary inbox.