Right now, the best way to log into macOS without having to type in a password is to purchase a Macbook Air or one Macbook Pro with a Touch ID sensor above the keyboard. It’s present on all Apple laptops now, although it’s not yet an option on desktop Macs, and it’s not possible to add it to the desktop by purchasing an accessory.
If you have a MacBook laptop with Touch ID, you can open the Apple menu, choose System Preferences, then select Touch ID and Add a fingerprint. Up to three fingerprints can be added per user, and you can also use the biometric security method to make Apple Pay purchases on your Mac in addition to using it to sign in.
When you next get to the login screen, all you have to do is place your finger on the sensor and you should have access (if there are multiple user accounts registered on macOS, you may need to be first to select yours). Fingerprint data can be deleted or replaced by returning to the Touch ID screen.
The other password-less option is to use an Apple Watch – this works on both desktops and laptops, and with all recent versions of the Apple Watch (check supported models here). Open the Apple menu, then choose System Preferences and Security and confidentiality, and check the box marked Allow your Apple Watch to unlock your Mac.
As long as Mac and Apple Watch are signed into the same iCloud account, both Wi-Fi and Bluetooth are turned on in macOS, and Apple Watch has been set up with a password, you’ll be directly signed into your account when your Apple Watch is brought closer to your computer.
Android allows you to log in to your phone using your face or fingerprint, although Android is Android, these technologies are implemented slightly differently depending on the make and model of your phone. Your handset can have both of these options, but at least one of them must be available.
In the case of Google Pixel phones, if you open the main Android settings app, then choose security, you can see the options available on your device. Tap one of them, such as Face unlock, to configure it.