Sure. Both parents die, neighbors / other family / friends might take you in. They might do this formally or informally (e.g. legally adopt you, or just raise you without doing the paperwork), to give you a better life than in an orphanage. Or maybe some aunt or uncle can’t have kids, but wanted to. It’s not that uncommon, I’ve met a few people in this category.
Vietnam has had a fairly turbulent history until fairly recently (quite an understatement). I don’t have many stories from those less peaceful times (my ancestors here are through marriage), but my impression is that it’s the sort of situation where adoption would have had to happen pretty often.
Oh one tangential tech story : You know all those scammy blockchain “projects”? Boy, they made a lot of t-shirts in Vietnam. A lot of the leftovers made their way to orphanages (a side effect of the economics of manufacturing is you always have extra, often containing nonsense text), so it was pretty common to see orphans with Bitcoin-whatever t-shirts for a while. So at least one OK thing came out of that technology.