The problem is how many random characters can you remember in your head?

A good encryption key would be around 32 characters to form a 256 bit encryption key.

You can do a fun game of encrypt the encryption key with a password but that’s just another vulnerability in the chain.

I recommend getting a PGP key stored on a yubikey and then encrypt all your notes with it since it’s all in markdown, I store my notes on Google drive and keep them decrypted in memory so that I can still use Obsidian.