I use Windows.
Teams has a head-shake-worthy UI and I have had issues in the past with external users (clients who are on their own domain, not part of my internal network) trying to access content stored in my Teams site. Other than that I haven't had too many issues with it. It integrates very nicely with other apps and with my Stream Deck.
I'm not surprised that it doesn't work the same on macOS. There are some features that are quite integrated into Windows 11 that would probably not work on macOS (ie, sharing a window by right-clicking its icon on the taskbar), and it is clearly an application built for Windows first (as are all Microsoft applications).
Try using Apple software on Windows computers. iTunes has been the epitome of sloppy application design for pretty much its entire life, and most of Apple's other past Windows offerings weren't much better. macOS is a 2nd tier market for Microsoft's products. They will spend the majority of resources getting their applications to run well on Windows, just as Apple spends the bulk of their resources getting their applications and services to run well on macOS and iOS. It's not necessarily due to wanting Windows to "look better" than macOS - it is more likely simply wanting to make sure their core customer base (corporate users) are happy.
Can't really comment on any of this, because I haven't used Teams for the Mac. I will say, your last complaint ("Teams overrides Mac settings for default microphone and camera.") is by design. Teams is a communications app, and for a very, very large number of users, the microphone that they want to use during a Teams call is going to be different than the one used for everything else on the computer. I have specific audio configurations on Teams because I don't want to use my Jabra headset for anything other than Teams calls.
That is probably because Teams file storage uses the same technology as OneDrive: Sharepoint.
Never had anything close to this happen, and I doubt that OneDrive is the cause. It is more likely your insistence on trying to use iCloud. The former is actually designed to be a secured, multi-tenant, multi-user file management system. The latter is not.