T4954: SOS representation and improvements in GnuPG made a progress, from a viewpoint of underlying crypto operations, for keeping the binary representation intact.
It allows stopping old practice of big-endian values and we identified&fixed bugs in libgcrypt and gpg-agent for stop modifying data silently (see: T4956 and T4964).

On the other hand, GnuPG 2.2 and other implementations keep old practice removing leading zeros in Ed25519 signature in the upper layer.

Given this situation, when importing, it is good to retain the binary representation of external input key, specifically, the data of the Ed25519 signature.