Running Nextcloud on a Raspberry Pi without internet

Would self-hosting a Nextcloud instance locally without an internet connection be viable?

Use case: Around 5 people need to share files over the network, collaborate on Office documents in real-time, use GitLab, and a To-do/Task management tool.

Beyond the initial setup, does any of these requirements need an active Internet connection, or can we all connect to the Raspberry Pi server via Ethernet?