Would it be possible for a billionaire to start their own ETF so they could rebalance/buy/sell securities in-kind without having to distribute capital gains?

Normally individual investors can't do in-kind exchanges of stocks/bonds without triggering capital gains, but many etfs are able to this.

Is there anything preventing a billionaire/UHNW person from starting their own ETF with the target allocation they want for their portfolio and rebalance/buy/sell inside the etf to avoid the taxes they would normally incurr from doing so?