#ProofOfReserve (PoR) in a #BitcoinETF is a mechanism that allows investors to verify that the ETF is actually holding enough BTC to back the number of shares that are issued. This is done by requiring the ETF issuer to publish the public addresses of the BTC wallets that they are using to hold the reserves. Investors can then use these addresses to track the movement of the BTC on the blockchain.
#ProofOfReserve is important for Bitcoin ETFs because it helps to ensure that the ETF is not engaging in any fraudulent activity, such as issuing more shares than they have BTC to back them. It also helps to maintain trust and transparency in the ETF market.
PoR is not possible to do with gold because gold is a physical asset that cannot be easily tracked on a blockchain. However, there are other mechanisms that can be used to verify that an ETF is holding enough gold to back the number of shares that are issued. For example, the ETF issuer could be required to provide physical audits of their gold holdings.