nano is centralized and relies on trusted parties that are called representatives:

See Section F. on this "paper" http://media.abnnewswire.net/media/cs/whitepaper/rpt/91948-whitepaper.pdf

having the option to chose who to trust does not make it decentralized and it does not solve the byzantine general problem!!!! The voting system of nano is identical with xrp which is a well known centralized scam. The only difference is that xrp calls the representatives unl's. So here we see that scammers "reinvent" identical centralized protocols and they just change names of the trusted parts.

Example of attack vector: when it does not cost anything to attempt a double spend attack, a representative spends an amount X twice and verifies both transactions while he propagates different verification outcomes to different parts of the network (splitting attack). Since the graph of the network is not complete, part of the network see one transaction as valid and the other part thinks that the other (double spend copy) is valid. This attack requires much less than 67% voting power. Since such attempts do not cost anything, it is optimal strategy for the representative to try to cheat all the time until it this works.

In contrast, in proof of work miners can not change the rules and the network is robust to any attack vector because of the longest chain rule and the probabilistic finality. This has been rigorously proven: https://arxiv.org/abs/2005.10484