You can either pick a battle that you cannot win (assuming you're not the one in charge of the many millions such a migration would cost). You can just deal with it, or you can look for better circumstances.

You say you're convincing people, management sees a trouble maker who's spreading unhappiness.

In my opinion, it's better to save your energy for something where it can make a change, not a futile attempt at trying to make an institute drop Outlook or Teams, or whatever shitty software we're talking about.

But hey, this is just my advice. You do you.

Plus it’s a backup location for stuff I simply can’t lose

It's not a backup. You're using "cloud storage".

I just want you to understand that, because Microsoft's online storage is not somewhere I would entrust with precious data.