All you need is to use ZFS or BTRFS locally to prevent master version bitrot and provide failover/redundancy, manually sync that to a separate "offline" HDD periodically, then setup a simple pi with tailscale + HDD at a family member or friends house, and rclone all your data to it (encrypted) as a cron job every night or week. This performs the function of a cloud provider (offsite backup); alternately, just manually sync the offline HDD once a month.

With this approach you're covered for accidental deletion, hard drive failures, bitrot, ransomware, and fire; possibly many natural disasters, depending how far away the offsite is.

Then you can just keep your most important data E2E encrypted in 1 or 2 cloud storage providers.