Visa's will be an issue in Vietnam. Uness you plan to live there full time (somehow??), learning Vietnamese probably isn't worth it as it's the only place that speaks it (unlike say Spanish or French)

Next door in Camboida, you can stay as long as you want. T visa and just extend. Philippines is mostly easier, English is widely used but its sea locked, and it's one of the most disater prone places on the planet and while the islands are amazing, travel is a bitch. Thailand is difficult with visas as well. Malaysia I know nothig of. Laos is an interestig place but super poor.

None of these places give you the same rights as citizens and they're all either very difficult, or very expensive to gain permenant resident status or citizenship.