I don’t have a favorite one and I love decentralized tech so I forked Lemmy to try and repurpose it for that. Honestly, I would have done it in Haskell or Purescript had the Lemmy devs not gotten as far as they have been with Rust.
It probably can’t have 1:1 feature parity with Shopify (actual commerce being handled on pub/sub would be a nightmare) but I at least intend to broadcast inventory changes using (a variant of) the pub/sub protocol. Instances will theoretically be run by vendors (or alliances of vendors).
I’m at the VERY early stages. I’m currently trying to build Lemmy using nix to declaratively glue together the patchwork they use to build it. I figure having it continuously roll with the original would be helpful for this rapidly evolving pub/sub world.