unfortunately it looks like Digitec and Galaxus do not support this yet - Synology and microsoft support this key

Unfortunately, you cannot log in to Galaxus with FIDO, but you can save the TOTP PIN on the Yubikey, this works with the Yubico Authenticator. You then have to read the Yubikey with the Authenticator and enter the displayed TOTP code when logging in. It is best to save the QR code when creating the OTP PIN so that you can register several, but at least 2 keys with this code. If you keep the QR code, you can use the code to generate the PIN on a new Yubikey if you lose a key.