SailfishOS is a scam who has collaborated with the Russian government before the invasion of Ukraine and continues to have ties to the Russian government. AuroraOS, used by the Russian government, is a fork of SailfishOS.
Curve Pay work well on GrapheneOS for the contactless payment, available for EU users currently, and I recently discovered a interesting a project that look interesting, which is actually in development.
"Are there other alternatives to UA there?"
Unified Attestation is an alternative of Google Play Integrity API, both are abusive, illegal and completely useless.
The AOSP attestation hardware is available since Android 8, is functional, and is neutral.
https://github.com/eu-digital-identity-wallet/eudi-app-android-wallet-ui/issues/287#issuecomment-4085348754
https://www.curve.com/
https://walt.is/
https://techcrunch.com/2016/11/29/jollas-sailfish-os-now-certified-as-russias-first-android-alternative/
https://en.wikipedia.org/wiki/Aurora_OS_(Russian_Open_mobile_platform)