Using PEX as wire conduit
Because this is an indoor run, I'm not entirely sure why conduit would be helpful, except in eventually pulling more cables, as you mention. That said, I pulled CAT6 through 3/4" PEX, and that was difficult. If you have 1/2", you're not likely going to be able to pull it through at all if it's terminated, and you probably can't get any more cables in there afterward.

Overall, I don't see a point to it.

If you wanted to do it, you could. You could probably use a PG fitting to connect it to boxes on either end. Keep pull tape in the PEX so you can pull more easily in the future. It helps to have twice the length of the run so you can hold it on either end, attach your cable, and pull without losing the pull tape on either end.