Being able to look up anyone by name in a public registry and see their exact salary would probably be a worst case This is the current state for public employees.

Anonymized data for companies larger than a certain size with job class (like levels.fyi[1]) would probably be a best case. However, if you want to get meaningful information about sex, race, age, & gender, this information quickly becomes identifiable for even moderate companies.

https://www.levels.fyi/?compare=Google,Facebook,Microsoft&tr...