Yeah, i’m planning public transport routes in advance with MetroMan for HK and for Shanghai i think i’ll rely mostly on walking + Didi/Uber. Zhangjiajie will mostly be about the park so it’ll be fine, and Guilin i’ll be doing lots of tours so MAYBE i’ll be fine with Google Maps + VPN 
Google maps is fine in HK, and includes buses when giving public transit directions, which are often much better than taking the metro. I’m also extremely fond of the app CityMapper, which gives the best transit directions in HK.
hk works well with Google, you’ll be perfect there.