Check out Proxmox + https://tteck.github.io/Proxmox/ + lxc container snapshots on the NAS and set up Proxmox backup server on the Pi. I find such a setup to be "all benefit, no giving up anything", contrary to NixOS.
A new programming language based on "mutable value semantics" has been renamed from Val to Hylo. It was a frequent complaint that the former name was too similar to other existing languages like V, Vala, and Vale. Mutable value semantics is a new way to efficiently pass around data structures without having explicit references/pointers present in the language and complicating semantics. Pointers are basically relegated to a status of a possible optimization that the compiler can perform at the assembly level.
AFAIU, SM2 computes the datetime of a next review, whereas Ebisu models a probability of remembering a given flashcard. It seems it’s a more straightforward representation that’s more amenable to implementing functionalities like “show me 10 least remembered cards”.