I found the following users who may fit your language exchange criteria:

Username	Date	Post Link	Relevance	Offered Matches	Sought Matches
u/tensuyu	2020-10-15	Post	`5`	English (Native)	Vietnamese
u/canikixit	2020-11-06	Post	`5`	English	Vietnamese
u/john_poko_here	2020-10-16	Post	`5`	English	Vietnamese
u/codethelifeyouwant	2020-10-25	Post	`5`	English	Vietnamese
u/mado_scientisto_	2020-11-10	Post	`5`	English	Vietnamese

Please feel free to comment on the above posts to get in contact with their authors.