It won't be 20,999,999.9769, neither 20,999,949.9769 which is the precise number.
Genesis block's reward isn't included in the circulating supply. It's block number 0, which takes place in no halving epoch. Counting starts from block 1.
But not impossible. Bitcoin which have simply not moved in a long time are not provably lost. The difference in your analogy is these bitcoin are already accounted for in the max supply. Capturing an asteroid filled with gold will inflate the supply of gold significantly.
And those abandoned coins will inflate the currency if they suddenly appear into the market. Similarly with gold, there's obviously a specific supply within this universe, but a minority of the ounces are in the market.
It's not impossible, but I consider it highly improbable for hundreds of thousands.