I use one of these: https://www.amazon.com/Feitian-ePass-NFC-FIDO-Security/dp/B0... . Plug into laptop when using laptop, hold against back of phone while using phone, and the form factor is non-annoying on my keyring with my house keys. I was shocked that YubiKey doesn't offer a single key that works for both phone and laptop.
The yubikey 5 NFC does. I think they also have a cheaper product which does FIDO2/U2F only also via usb A and NFC too. Before that, the yubikey neo did both NFC and USB A.