There's several well-known ones that work, and additional projects like Streisand[1] which exist to allow a roll-your-own solution. In all cases, VPNs that work are ones that obfuscate that they're VPNs via varying methods.

Otherwise, as others have said, mobile roaming data is functionally identical in that the data appears to the internet as having come from your home country. Hong Kong offer a few plans that are (relatively) affordable and roam into the mainland.

[1]: https://github.com/StreisandEffect/streisand