Here is a non-exhaustive (non-binding) list of services and applications compliant with the FIDO U2F standard.
BoxcryptorDropboxFiles.com Google Drive
Amazon Web Services Google Cloud Platform
G Suite for Education Hangouts SalesForce Follow Link
Blogger ShopifySilverstripe WordPress (2FA plugin) YouTube
Binance BitfinexBrave Coinbase DSX
Bitbucket Github GitLab Jira (2FA for JIRA) Sentry
1Password Bitwarden Dashlane
AuthStack Avatar AxiadCentrifyDaon DUO ForgeRock Gluu Green Rocket HelloID IBM Security Access Manager ID.me Idaptive Keeper MicroFocusOkta OneLock OneLogin PingIdentity PrivacyIDEA PushCoinRohos RSA SecureID Access Sign&Go SSO (Ilex) Thycotic Trustelem (WALLIX) WSO2 XTN Cognitive Security
Gandhi GoDaddy IPS Hosting namecheap opalstack OVH
AppGate ISL Online SAASPASS StrongKey XONA
Facebook FineFriends Twitter YouTube
Isosec
Linux (Debian, Ubuntu, Fedora) Microsoft Microsoft Edge Browser
FastMail Gmail Hey