Just an FYI: OVH have anti DDoS builtin to their VPS and dedi servers, so I dont use CloudFlare. Never have, I run all my services (except DoS mistigations) my self.

So your looking for a file share not a notification system, that’s the big difference.

Notifications don’t tend to have massive file attachments

For a giggle, what about home assistant?

I know your looking for self hosted, but I can recommend pushover. It’s got a lot and the apps are amazing, for $5 for a life time license it’s great.