Can confirm. my 2018 trip digi roaming can access everything, WA, Line, FB etc.

VPN failed me, i subscribed to ExpressVPN too and it didn't work at all with local sim, although it is advertised to be able to circumvent the great wall.

speaking of local sim, you can walk in to any china telecom store (official one, not authorised reseller) and get visitor sim.

I'd suggest just use roaming for the best experience.