so far not many mechanisms can be used to do what you asked for.
1. You can check LLAP UI to see which queries is running, and how long it has been running. You can then dig into each node to see how many executors are used to run.
2. You can tail the LLAP log to see the mappers/reducers are used running for queries. --- This is most close one to what you ask for.
3. In the Tez view who are the owner of the query, you can check running status as well, and you can see the swimming line to further understand the cost for each steps within the query. But this will be available after the query is finished.
The intention of LLAP is for queries with short turn around time, long running/larger query should not be part of LLAP process.