No question is stupid except the one not asked.
Does your radio have a pocket or bin above or below it or is it a double-din sized unit.
Most Toyotas have a double-din opening, but some have a single-din radio with a pocket taking up the rest of the space. You can replace the unit with any radio single or double-din. It is not necessary to install a double-din, you can just use the pocket and a single-din unit.
If you are looking for an inexpensive upgrade, you can get a used Toyota unit. These are readily available on eBay and are plug and play.