On the policy points they're actually a lot less radical than I expected. Community oversight of police has to be done in a good way. Ask anyone in the UK about the police and crime commissioners
In most municipalities a police commission is appointed from community members. If there is an investigation into police behavior the results come before that commission for oversight. This system should work as BLM wants, but there are a couple of problem areas. One problem is that the commission is representative of the mayor and not the community and it becomes a rubber stamp for the internal investigations. Local elections are really the only cure if this problem is occurring.
Another problem is due to the size and organization of big city police forces. There still will be a commission, but typically just one for the whole city. That limits how representative it can be. Creating many smaller commissions might fix that, but it runs into the problem of the single hierarchical structure of the police force and union. How does one integrate many small commissions with a police force with a single command structure?