According to this other answer, this is a question of "key formats". OpenSSL uses the key as seed and hashes and clamps it in preparation for generating the public key:
An ed25519 key starts out as a 32 byte seed. This seed is hashed with SHA512 to produce 64 bytes (a couple of bits are flipped too). The first 32 bytes of these are used to generate the public key (which is also 32 bytes), and the last 32 bytes are used in the generation of the signature.
openssl genpkey -algorithm ed25519 | openssl pkey -text
Can I have OpenSSL omit these steps so that it generates the public key directly from the key as integer?
... or can I work around this using a different command?