Last time I went to China (2018) you could simply get a China Unicom Hong Kong SIM card and then use that to roam in mainland China. With that you'd get the Hong Kong censorship level, which is much much less restrictive. No VPN or anything needed apart from the SIM card itself.
I'm in China right know with a Mainland/Macao/HK eSIM. My Chinese friend has to use a VPN to access Instagram as did I when I was connected via WiFi in mainland China. Using the eSIM connection I could access Instagram and Youtube without any issues, likewise here in Hongkong (with WiFi).
I didn't investigate how large the difference is, but Hongkong traffic is still treated more liberal.
