There's 5 races in Guildmasters Guide to Ravnica: Centaurs, Minotaurs, Loxodon, Vedalken and Simic Hybrids. Centaurs and Minotaurs are in the Monster Manual and assumed to be in most worlds. Loxodon might be in Forgotten Realms as the Loxo, and the Loxodon like the Vedalken are in a few other MtG worlds too. I'd argue that Vedalken could be related to the Mercane/Arcane of Spelljammer at least superficially.

So the Simic Hybrid having the "Simic" Combine in their name are more specific to Ravnica. But the fact that being magical science experiments is the main thing about the Simic Hybrids, I feel they could have all sorts of places in other published worlds and homebrew worlds just fine. I remember Ravenloft had "Broken Ones" for it's Island of Doctor Moreau analogy, so I think a Broken One could be a Simic Hybrid. I don't think they'd be out of place in Eberron, as they either be experiments or mutations brought one by Khyber or Xoriat.

In some cases they might be people created by Aboleths or Krakens. Any other ideas where a Simic Hybrid might come in, or other names they might have in other worlds?