Exchange-traded fund (English Exchange Traded Fund, ETF) is an exchange investment fund, that is, it is an investment fund whose shares are traded on the stock exchange.
Operations on ETF shares can be made throughout the trading day, and their price varies depending on the activity of market participants.
All ETF shares must be fully secured with assets in the manager's account
In the case of bitcoin, transactions will be made not with bitcoin itself, but with ETF, which saves investors from having to have bitcoins.
The purchase in this case, as you have already understood, happens only indirectly.