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yubioath-desktop
Discontinued Yubico Authenticator for Desktop (Windows, macOS and Linux) and Android [Moved to: https://github.com/Yubico/yubioath-flutter]
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InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
U2F and FIDO2 are 2FA. If you mean support for (T)OPT, then that is currently not possible. https://github.com/solokeys/solo/issues/208
You can use Yubikey for Steam no problem, both in the desktop and mobile Yubioath apps. You just need to extract the TOTP code from the android app and import it into Yubikey.
NOTE:
The number of mentions on this list indicates mentions on common posts plus user suggested alternatives.
Hence, a higher number means a more popular project.