Site workflow querying multiple lists

if you mean to query multiple lists but each list with its own action, then yes that;s possible.

but you cannot query multiple list from within single action.

Hi emha. I actually am inquiring about your first statement. Querying multiple lists with one workflow but seperate actions to each list.

as I mentioned this is not a problem at all ...

Would you mind giving me some pointers or direction on how to do this? Thanks

I think you're making it too complicated with the for each, but then again, I'm making an assumption on minimal information. 

In order to query multiple lists with separate actions, you just have one query list action follower by another. 

https://help.nintex.com/en-US/nintex2016/current/#sp2016/Workflow/ActionsCore/QueryList.htm?

You can utilize the filter options if you want, or just pull all items in. Then you store the returned values into a variable. Then, if you want to query the second list based off the first list, you can use the variable results from query 1 to filter on query 2. Then you store those results in a different variable. 

For both you would store them in a collection if you're expecting multiple results, or (most likely) a single line variable.

there is not any specific in using query list action.

you can use them, and as many as you need,  just like any other action.

if you have any problem with your design, you should provide more details what exactly you are doing and trying to achieve so that we could guess what's going on.