At OERu we prefer using BigBlueButton, an outstanding open source video conferencing tool that was designed for teaching.

There are excellent open source alternatives, for example Rocket.Chat and Mattermost for digital messaging.

There are open source alternatives for these technologies avoiding the need for users to sacrifice their personal data. At the OERu we use Nextcloud with OnlyOffice for collaborative document editing.

A useful summary for getting started with online learning, rather than emergency remote teaching. I don't see a copyright statement, so we need to check with Contact North | Contact Noord if they have applied an open license. I see that their main website is CC-BY-SA.