I use Syncthing [1] and restic [2]. I use restic to backup the important things to several backends, including a home server (Raspberry Pi equivalent) and cloud storage. If you worry about getting your software/operating system up and running in the same way as before, you can use a declarative operating system such as NixOS [3].

[1] https://syncthing.net/ [2] https://restic.net/ [3] https://nixos.org/