Stop apologizing for them. It's literally two more clicks, and anyone who has gone through the flow expects those clicks. Also, if Installer never realizes it installed something, it won't even offer to delete the installer .pkg.
I'm pointing this out not as an excuse for Zoom, but as an example of long-standing friction in macOS. I think it's worth pointing out they've had the same motivations in the past. Like Dropbox, I hope the OS improves so this isn't necessary and knowing this is a pattern (and not a one-off) with the company I will avoid them when possible.
There are already good solutions to this issue. In particular, simply placing the app package in a zip file, then checking to see if it's installed correctly when opened.
My annoyance with macOS/Apple is that this isn't standard and default. Therefore, not consistent and can be confusing (especially if you're trying to join a call in progress). Because of this, Zoom chose to reduce the number of dialogs thrown up.