How can I store files securely?

I have tons of files that are of a sensitive nature, ranging from 2FA recovery codes to legal documents (e.g. contracts, employment-related stuff), copies of my passport, tax documents, financial documents, etc. Basically, a kind of digital ring binder.

Right now, I keep them in an encrypted "sparsebundle" volume (I use macOS), which I tend to just keep mounted, because it's tedious to type a password every time. This means a piece of malware or a hacker could gain access via some kind of exploit, Chrome extension, etc.

I thought about writing something that automatically unmounts it after a while, but I don't want to go into a complicated project.

I would like a solution like so:

- Allows me to organize files by folder, preferably as a real file system

- Requires a password (and supports Touch ID) after some idle period

- Is fully encrypted

- Can be synced peer-to-peer to other devices, so I can access the same documents on my phone

- Not stored in the cloud

Any ideas?