The integration with Meet consists of a single "invite to video call" button that creates a new video call and inserts the link into your message. There's no option to stop people from inviting you to new calls/set your Google chat status as busy when accepting a call.
Meet itself is also frustrating to use for anything more than a 2-3 person meeting; it doesn't display more than 4 video feeds at once on your screen. It's also unable to save settings between video calls (if you don't want to have incoming and outgoing 720p streams all the time you have to change the settings at the start of every call). Zoom and even Jitsi are both miles ahead of it.
There is no reason to use either product besides the fact that they come with enterprise Gmail accounts. They both still feel like prototypes or minimum viable products (especially Chat).
A mobile only consumer proposition is useless. Sounds like Google's internal strategy here is still a disaster.
Desktop -- Meet/Chat converging and getting a unified UI for business/desktop users.
I think it is taking time, but it's finally happening and Hangouts will officially be shut down when the merging happens.