How can I create a geth-clique POA network as an Ethereum sidechain to mainnet or testnets. what is the simplest ways to do that? are there any frameworks that can be implemented easily
In my opinion choosing the sidechain type is not so important. What is important is deciding on how the communication happens with the main chain and what kind of security features are present.
So you first decide what layer 2 solution you want to use: Plasma, Rollups or something different. After that you create the sidechain and connect it to the mainnet with the chosen solution.