Re: But what about the apps?
who actually works with O365 in the browser?
There's also the problem of the online versions of the apps being less "fully featured" than the local versions. One child had to produce a big report for school in Word with some very specific layout guidelines, including the use of text boxes. Online app can't do text boxes, which was a right royal pain in the backside during lockdown when it was impossible to go in to school and use the "real" apps on the school computers - we have no copy of Office at home and while he was very pleased that school provided him with a Chromebook, it, too, can only access the online apps.
He says there's a problem with Excel too, some restrictions on size of sheets and something that meant the graphs he made in the desktop version wouldn't show in the online version, and vice versa. In fact at one point a Word document became corrupted and un-editable, possibly also something to do with embedded Excel graphs and swapping between desktop and online apps. That was partly solved by saving it locally and loading and re-saving from LibreOffice. While this didn't fix everything in the online app, it at least became editable again, and when he was next in school, loading into the desktop version everything magically re-appeared.
Easy swapping of accounts in Teams would solve an awful lot of problems, but not the ones where you actually need to be online to two (or more!) accounts at the same time, which is something my wife has to do occasionally. Her solution is to use a laptop for one and an iPad for the other, but it's not ideal. Private browser windows might work, but trying to explain it to her...