This page is our investigation of cross-play feature in game called Hell Let Loose: Vietnam. We also want to mention that - we always put manual efforts to find the precise, valid, and what is more important official information about different game features without using AI.
Yes, Hell Let Loose: Vietnam will support cross-play at release. Players on PlayStation 5, Xbox X|S, and PC (via Steam and Epic Games Store) will be able to play together.
This information is taken from the official Hell Let Loose: Vietnam FAQ, which you can check for yourself by following this link.

Games can have different cross-play combinations, for example the game can have cross-play between PC, Playstation 5, Xbox X|S, but not between old generations like: Xbox One, Playstation 4, PC. To avoid any misinterpretations, we group them into so called "cross-play variations".
Any store inside the cross-play variation have a cross-play only with a store in the SAME variation. We also want to notice, that we put into variation not platform, but store + platform. That is required because some games, for example, can have cross-play between a Playstation 5 and Steam, but not Playstation 5 and Epic Games.