Yes, but that's not circumventing anything. That's an essentially approved method for foreigners specifically because they don't care about keeping foreigners within the GFW.
Once that foreign esim is behind a GFW equivalent of whichever country it is from, what then?
> I think places like China put in a lot of effort
Yes, which is why China was tricky.
1. A government has authority for a geographical "box".
2. The government succeeds if it can plug all the "holes".
3. Rogue anti-government behavior punches new holes all the time, which is an endless battle.
In the case of the internetwork, we're two underwater cable cuts away from severing the planet asunder and effectively patching most of the "holes", but that would also destroy most of the economy, so no government really wants to do it.
I guess my political statement/point is that as long as there's too much to track, we're all safe, so making more things across more domains makes everyone safer.