I'm searching for a solution to get my list viewable on different sites (or site collections if possible). But i would like to do it with oob. So my purpose is to have a single list that multiple sites would share and use values from it as look ups but i'm not aware if we can do this with sharepoint.
You've found the headache that a lot of administrators deal with when trying to share data between site collections. The short answer is you can not do this out of the box. You are able to do it in sub sites because all the data in theory lives under that one site collection. If you want to pull data from a list on another site collection you will need to consider a custom solution.
You could consider some sort of roll up or exporting feature from one list in site collection A to the list in site collection B, or a workflow to push that data across, but performance will be an issue and something to consider.
Kindly check here