Yeah it's not fun.

Vanguard offers a bunch of ETFs so I can't exactly give you a solid answer.

One of their specific etfs (VTI) tracks the CRSP US Total Market index [1] which has its methodology described here [2] and looking at the "CRSP INVESTABILITY SCREEN SUMMARY" it sounds to me like SpaceX would be added to VTI after 5 days ("Seasoning of New Securities - 5 days or greater if satisfying the fast-track IPO rules".

[1]: "The Fund employs an indexing investment approach designed to track the performance of the CRSP US Total Market Index (the “Target Index”), which represents 100% of the investable U.S. stock market," https://personal1.vanguard.com/pub/Pdf/sp970.pdf

[2]: https://www.crsp.org/wp-content/uploads/guides/CRSP_Market_I...