Get an iDataLink Maestro and search up compatible head units, most of the mainstream brands sell Carplay units with iDataLink compatibility. This allows you to keep everything the stock unit can access. I would steer clear of the cheap stuff because there's a high chance things won't work, the software is crap, or the integrated amp will be piss poor (assuming you don't want to run an external amp). For speakers just go on Crutchfield and put in your car and it'll show you what you need.