The problem is Coinomi is not opensource anymore. My idea was to create decentralized open-source wallet. Since they closed the source, we have no idea what they do under the hood. Let me try to fork some native bitcoin wallet and then examine the code of QtResearchWallet. I think that would be a good starting point for a total newbie like me :) I'll share the github as soon as i manage to get something that at least sync with the network.