> There's a movement online to get people weaned off big tech and surveillance capitalism.

This is a niche movement at best, ironically mostly followed by people who are already concerned about privacy. I doubt they manage to convince many others into joining them and abandoning big tech. My own attempts at doing so have mostly been met with a few responses: "I have nothing to hide", "It's too inconvenient to switch", "I just use it for X and don't spend a lot of time on it", or "I don't care".

> The thing about privacy online is that it's hard to measure, since many opt out of telemetry

Hah, right :) I think we can track it by simply seeing how the user bases compare between big tech and privacy-focused services. So far the numbers are several orders of magnitude apart, it's pointless to even compare them. There are many reasons for this, and I hope things keep improving, but I doubt we'll even make a dent in 10 years.