Computing PGP ed25519 and curve25519 keygrips? There are public key algorithmic differences for how PGP computes fingerprints and keygrips. For the v4 protocol, fingerprints are not exclusively computed from public keys while keygrips are. RFC 4880 makes no mention about keygrips. 

After digging into code at 10 different places in the the libgcrypt from https://github.com/gpg/libgcrypt/blob/master/tests/keygrip.c, it is still a mystery as to how PGP keygrips are computed for ed25519 and curve25519.

Fortunately, the keygrip.c provides the two normative example test vectors:

 1. ed25519: 
    publicKey = 773E72848C1FD5F9652B29E2E7AF79571A04990E96F2016BF4E0EC1890C2B7DB,
    keygrip   = 9DB6C64A38830F4960701789475520BE8C821F47

 2. cv25519: 
    publicKey = 918C1733127F6BF2646FAE3D081A18AE77111C903B906310B077505EFFF12740,
    keygrip   = 0F89A565D3EA187CEA39332398F5D480677DF49C


Can someone provide the operations on the public keys prior to the sha1 hash that creates that creates the keygrip output? (Thanks in advance.)
Keygrips are not part of PGP at all, they're just an implementation detail of GnuPG's key storage architecture specifically (which uses a common key store for PGP, S/MIME, and SSH).

As you saw, GnuPG uses libgcrypt for cryptographic operations, and the keygrip calculation can be found in cipher/pubkey.c where it's just a SHA-1 hash of the public key's parameters.