I don't think VN has much of a "scene" exactly. In the cities, I think gay people just blend into the general Nightlife. So there's no real need for specific gay bars, as such.
Plenty of action on the apps. I'm a plump, pastey, white dude in my late forties, but I get plenty of offers on blued and Grindr, mostly from young guys. Usually, they want money, but not always.
I like Vietnam, generally.