Are there any free/open source alternatives to Microsoft Teams with text/voice channels, group video calls + screen sharing, file sharing features etc.? But it should be able to be deployed on an independent server on your own machine or cloud.
You could go with Nextcloud, which you can deploy onto your own servers.
- file sharing: provided out-of-the-box. You can share to other members of your own instance, to Email-addresses or even anonymously, including password protection if needed.
- ext/voice channels, group video calls + screen sharing are provided by the **Nextcloud Talk app.
Nextcloud is open source and comes fee of charge. Like Nextcloud Talk, there are many more apps to extend the functionality. On a side note: the German government decided for Nextcloud for their Bundescloud, which strongly speaks for its maturity.
What you didn't ask for: there are also several apps for mobile devices, to keep data synchronized with your Nextcloud or have a "native app" for e.g. Talk – though you could use all of it simply via your web browser.