These! Kind of a pain to get to those bulbs, but worth it
Lights: https://www.amazon.com/gp/product/B072JLWGQX. I'm happy with them. Nice and bright. Had some others that flickered constantly, but these are good.
Those slots are for the (bluetooth?) mic that connects to the OEM radio. It's a pain to repurpose and of course I replaced the OEM radio long ago.