I just learned that I have to enter the email address of my invitee and the invitee can only use this address and no other to sign up for Proton Wallet early access.

If this is to privacy eroding for you, don't ask me for an invite.

Maybe you can bypass this by sending me a burner address and in the next step invite yourself with your desired email address from the burner address. This would leave me without knowledge about your email address. However I don't know if you get an instant invite after creating a Proton Wallet from an invite by me. 🤷 If you give this process a try, please inform me about the outcome.