The tables at SSH ciphers indeed refer to ciphers used within the SSH protocol. They have no relevance for private key formats. Supported private key formats are covered by Private keys page, but detailed matrix of encryption algorithms + key derivation algorithms + hash algorithms is not currently listed there.
But basically, we aim to support all encryption algorithms used by the the supported key formats, so lack of support for new OpenSSH format keys encrypted with AES/GCM or ChaCha20/Poly1305 is an omission. Until now, we were not even aware of them - OpenSSH key format is proprietary and insufficiently documented.
We will add support for new OpenSSH format keys encrypted using "chacha20-poly1305@openssh.com" or "aes256-gcm@openssh.com" to one of the next releases - thanks for bringing this to our attention.