Bitcoin Core 17.0 - How to calculate balance with zero confirmations included (watch-only)? Is it currently possible to calculate balance including UTXOs with 0 confirmations, for watch-only addresses?

getbalance "*" 0 true


includes utxos with 0 confirmations only if that address has private key in the wallet. Balance from watch-only addresses is added when corresponding UTXOs have at least 1 conf.
No. Bitcoind requires at least 1 confirmation before a utxo amount is added to your watch-only address balance. Which makes sense, as it can still be trivially double-spent whilst it is not yet confirmed.

Related question: bitcoind sendfrom with minconf=0