Regarding your mutual backup idea, I love this and I've wondered why this hasn't taken off as a Thing in response to how many of us are untrusting and DIYers in this era of cheap storage and bandwidth.
Indeed! I'm not sure why I don't already have three hard drives from friends, it's 10x cheaper than S3 or Backblaze B2 or any such thing. I've had this idea for years, but seeing that someone else built exactly this[1] while also having time for it soon gave the idea another push.
