I've never known a reason to expose the docker socket to Nextcloud. It's certainly not required, I've run Nextcloud for years without ever granting it socket access.
Most of the things on that linked page seem to be for Docker rather than Nextcloud, and relate to non-standard configuration. As someone who is not a political target, I'd be pretty happy that following Nextcloud's setup guide and hardening guide is enough.
I also didn't mention it, but I geoblock access from outside my country as a general rule.