ukraine just relies on electronic signatures (usually issued by banks) for online identity verification. (these are usually just jks keystores)
you can put them on hardware keys if you want to

alternatively, bankid or diia can be used

• bankid pulls info directly from your bank, using online banking credentials

• diia is an electronic ID app and comes with built-in identity verification and signing features (authenticated by biometry/phone pin + a face scan with specified action (e.g. blink or tilt your head) + 5 digit pin).
  the app can be activated by scanning the NFC chip in passport or id card + doing a face scan, or by using the BankID system. (if you already have a bank account, or your phone doesn't support nfc), which is slightly faster as the face scan is quite annoying (as it requires perfect lighting conditions)
  the key used by the app cannot be exported tho, if you need a jks keystore, the only option is to get one from the bank.

(By the way, the app's name, "дія," is quite clever. It stands for "action," but it's actually an acronym for "держава і я" which translates to "government and me.")