I think these travel guides are quite completed, by the way, Vietnamese people are now open mind, there are some groups for gay online, you can search them on facebook.
Here are the travel guides for Hanoi & HCM City:
Hanoi Guide: https://www.bestpricevn.com/travelgu.../Hanoi-30.html
Hochiminh City Guide: https://www.bestpricevn.com/travelgu...h-City-14.html
Good luck!