I support businesses that are expanding into the Vietnamese market.
I support businesses that are making their way into the Vietnamese market.
I support businesses that are making their foray into the Vietnamese market.
日本語では「ベトナムに進出」と言いますが、ビジネスに関しては「～の市場に」という言い方をします。
expand into the ~ market
make one's way into the ~ market
making one's foray into the ~ market
どれも「～市場に進出する」という意味です。
businesses の代わりに companies と言っても大丈夫です。
日本 
