Oracles are always going to be less decentralized than a distributed blockchain VM. Chainlink's (oracle platform) approach to this is to have oracle nodes post

Oracles are always going to be less decentralized than a distributed blockchain VM. Chainlink's (oracle platform) approach to this is to have oracle nodes post a bond that can get slashed if the computation is deemed invalid. But most Chainlink oracles have 21 or fewer nodes. This is fine for supplemental data but would be vulnerable to all the same attacks that DPOS chains have suffered if used as base layer consensus.