Back when I was in school (damn does it make me feel old to say "back in my day") I just had one device and collaboratively working on a presentation meant splitting up the parts and everyone sent what they wanted to have on the slides to the one group member who actually created the presentation (and made sure the format and style of bullet points were coherent) in zipped archives via e-mail. Also, we had to either bring our own laptops to show a presentation (at least the schools had beamers) or print that shit on literal OHP transparencies.

Anyway, there are open source alternatives to Google Docs, OneDrive, etc. You could go the NextCloud route or use Cryptpad, both can be either subscribed to through various platforms or even self hosted.

Just to add to your anecdote and provide some alternatives if someone reading this needed to know.