I've done this to lots of old cars too, but I'd never claim it to be as good as an interior built for carplay - typically the sight lines to the display are com

I've done this to lots of old cars too, but I'd never claim it to be as good as an interior built for carplay - typically the sight lines to the display are compromised if doing something like a double-DIN carplay head unit from Sony et al etc. I've generally had no issues finding adapters that allow legacy steering wheel controls to control the aftermarket head unit/carplay too. However, the display often ends up too low on the dash in older vehicles with a retrofit, modern cars typically place it higher on the dash almost level with the instrument cluster to make it easier to check for navigation etc, most modern cars can even sync carplay directions to a secondary display in the instrument cluster. The siri mic solution can be compromised too, depending on the vehicle and how you fit the mic. It's livable of course, but often not optimal.