Yes, I have it under a subdomain I own on cloudflare. Then it’s behind nginx proxy manager on my server which takes care of the ssl too. I have fail2ban too so consider it enough security for if the user passwords are long enough. You can set minimum lengths if letting others use it, or in my case I helped family set it up and made them have strong passwords.

Like others have said, the apps cache everything locally. I have used it without issues with no mobile Internet (e.g. for my cc pin numbers I store on there when i was out in the country with crap reception). I guess you’re more likely to create accounts at home anyway but if you have to when out, it would sync whenever you have it back on the lan.