On Windows, you can use a variety of Android 2FA apps. With a bit of messing around, you may even be able to get the Authy Android app working. On other platforms, there's a variety of open source and not-so-open source TOTP apps you can use instead.
Authy does have some proprietary stuff (partnership with companies for auth push notifications, for example; I've seen this on Twitch) but most companies just use the TOTP/HOTP functionality that's available in all manner of apps.
Some password managers allow you to do 2FA autofill, I’ve been moving mine into 1password, but when it doesn’t autofill it isn’t as fast to go pull it up manually as it was with authy, still worth it overall, though
Authy does have some proprietary stuff (partnership with companies for auth push notifications, for example; I've seen this on Twitch) but most companies just use the TOTP/HOTP functionality that's available in all manner of apps.