The best selling point of Ordinals is that they are embedded in the most secure and decentralized blockchain, Bitcoin's. They could be implemented much cheaper in a sidechain, or an altcoin, but this would result in just another useless token concept which would be forgotten after a couple of months. Think of an altcoin that can survive in the long term, allows you to embed trash and is equally censorship resistant such that its community would be highly discouraged from excluding that trash specifically. I don't think there is.