Share single passwords with others

Welcome to the forum, @ajimix! The best way to share data in 1Password is through the use of a 1Password Families or 1Password Business account. This allows for very flexible and secure sharing within the team/family, and it even allows you to invite external guests to the team temporarily, for just such cases where you need to transfer one or more 1Password items to someone who's not a member of your team.

Outside of that, there is not currently any sort of "one time link" option, as there's really no secure way to do that from within 1Password itself. Your data within 1Password is encrypted by AES256 using your Master Password (and if you have a 1password.com membership, your Secret Key also) to derive the actual encryption key that en/decrypts your data. You don't want to share your Master Password with anyone else, and they can't read any of your 1Password data without it, unless you export the item in unencrypted format such as .1pif or .csv.

Different 1Password apps have different options for sharing if you're not using a 1password.com account; for example, if you're using an Apple device, you can use Messages, which Apple claims to be end-to-end encrypted (start on page 60). If you and your intended recipient are on the same physical WLAN network and are using Apple, you can use AirDrop, which is similarly secure. On other platforms (like Windows), the options are more limited.