When signing a pubkeyhash UTXO, it is required to provide both a signature and a public key. The public key is duplicated and one copy is provided to
op_checksigverify to ensure the signature is valid, and the other copy is hashed to ensure it matches the pubkeyhash.
In theory, is it possible to build an opcode like
op_checksigverify_pushkey that takes only the signature of the transaction and extracts the public key from the signature? With this it would be possible to only specify the signature and no need to provide the public key. The public key of course could be arbitrary, but would fail when hashed and compared against the vout pubkeyhash.