... and there are half a dozen ways to get around that too. You could proxy everything through a function that base64 encodes everything. It's an arms race.

Besides, I was talking about my server directly sending data to Google Analytics without JavaScript on the client side. GA has strong adherence to GDPR so there's no legal or privacy issues I can see with that.

You're not thinking this through. Any request can be proxied. Ublock won't block GET requests for `index.html` or other assets, nor even random POSTs to `/detail` from button clicks and such

Just speaking from first-hand experience.

This isn't detected automatically though, right? Someone would have to reverse engineer your setup and add it to the lists?

uBlock does detect this automatically, without reverse engineering your setup and adding it to their lists.

This assumes you self-host analytics.js and proxy GA API requests through your domain without changing path/query. If you manage to reverse engineer analytics.js and change the path/query AND proxy through your own domain, then this likely wouldn't be detected. But there's a chance that Google will make changes to analytics.js that aren't compatible with your reverse engineering it, and your setup breaks.