They've shoved all that functionality into the Gmail app. I actually uninstalled Gmail because it became the default app to open Google Meet video calls, even with Google Meet installed. I don't need my email app asking me for video and microphone permissions...
This specific case is more of an artifact of iOS's inability to handle multiple apps declaring the same URI launch scheme cleanly than a problem with Gmail on iOS, in my opinion.
Picking a default handler for a given scheme seems like a problem best solved at the OS level, and I don't even know how an app developer would be able to fix that.
As Apple has been steering people away from custom URI schemes, I doubt they will ever support platform-level dialogs for the user to select an app or a system wide 'open in' default.
Coincidentally, the methods used for this today in macOS (in apps that prompt to set themselves as the defaults, or populate a drop-down) are deprecated.
....which I said I did but still could not opens video chat links in their dedicated video chat app because it open Gmail anyways, which then just crashes with an error that it doesn't have permissions
https://apps.apple.com/us/app/google-chat/id1163852619
https://apps.apple.com/us/app/google-meet/id1013231476