All went relatively well, until I needed to share the slides with others using Office 365: my first try of sharing the slides by clicking the Share button inside Office for macOS caused it to upload to SharePoint as read-only: not even myself (the document owner) could edit it.
I said "fine, I will just upload the .pptx file manually", and it worked well enough, until the file came back with some comments for fixes: now if I clicked the "Open on desktop" button, it kinda created a local copy that I could never sync with the remote one, but they're still clearly the same file because it did show as the same file when I went to properties on both desktop and web versions.
At that point I was getting really pissed off, so I started editing locally and copying my changes to the remote version. Office still had one more surprise: I could copy whole slides remotely, but copying part of a slide (say a rectangle form with some text) would instead convert that part to an image. Seriously, what the f*ck Microsoft?