Question about Nothing Phone (2a)

Yes, why not? The device runs Android 15, i.e. the latest Android version and the official Google Playstore etc. is also available.

We have both a Nothing Phone 2 and a 2a in the family, the banking apps are only installed on the 2 and everything works as it should.
As the 2a is almost identical and is being rolled out with the same Android version, there's nothing to stop it.
Twint at least works without any problems and Google Pay with NFC also works.