Good luck! From a fellow unionized digital worker. I work at Kakao, a South Korean firm known for KakaoTalk (the dominant messenger application in South Korea).
My impression is that among South Korean digital companies, unionized companies transitioned to remote work earlier.
2) Most US companies had no problem going full remote some time during the spring of 2020, doesn't look like "unions" play a big role there.
The most prominent benefit is fight over overtime pay. In fact overtime pay is what triggered unionization in South Korean IT sector. Pre-unionization, basically no one in South Korean IT paid overtime. It is legally a gray area. Then Naver (the dominant search engine in South Korea) unionized over overtime pay and won. Other companies, including Kakao, quickly followed and all won. Naver union shared their know-how to other union organizers.