but Since the address in question (P2PKH) contains newly generated block rewards from solo hashing over a good period of time, but none of which were spent (unfortunately, and neither do I have an signed message for this P2PKH address) - is there any reason why scriptSig from generation transaction recorded on main net not providing me my public key? maybe the offset I'm copying is incorrect - or it is just impossible all together
Since it's P2PKH and not P2PK, it's impossible.
Even if it's from multiple coinbase transaction output, Pay-to-Public-Key-Hash still wont show the public key until it's spent.