Not OP, but I feel like moving from Google to Zoho is just kicking the can down the road. You don't know how these big corporations will change their product or (more importantly for cash strapped organisations like Universities) their pricing structure.

It seems like a much safer to bet to move to an open source project instead. The costs of hosting it would be well known and predictable.

Which is funny because if you want lock-in there's no better way than to offer end-to-end encryption.

Does it prevent you from exporting the data, changing the vendor, changing the application?

I think you have a wrong view of „lock-in“

I'm a big fan of Zoho and I use them for one of my organizations, but having an open source option is huge and a massive selling point even over Zoho.