Would it be able to reproduce strategies that involve options?
I recently learned of the SWAN ETF, which captures (or attempts to) most of the S&P's return with significantly less volatility. It holds mostly Treasurys, plus options that are in the money if the S&P gains a certain percentage[1].
https://www.amplifyetfs.com/swan-holdings.html
They had to create the "S-Network BlackSwan Core Total Return Index" for it.
[1] They look to buy a year out every six months, but I can't tell for sure; it currently has SPY210618C00265000 (call at S&P = 2650 in June) and SPY 211217C00324000 (call at S&P = 3240 in December)