Yea, a bot that just runs your Vanguard account like betterment/wealthfront would but without their fees would provide a huge amount of value to people.
you can set it up to manage your own portfolio.
i.e. you can set yourself up as an RIA and a client of your own firm, the on-boarding process for both sides takes 45 min total. And if you are good enough with writing code you can script all your setup data (we have examples of that).. than setup is even faster.
Once that's done you can run the rebalancer on tolerance or quarterly (time-frame) basis to rebalance your own portfolio without any fees.
You'd only pay fees with your custodian if you decided to execute the trades proposed by the rebalancer.
