Yes, there is some investment involved but for me it was a no brainer, I'd a pretty useless AppRadio2 so my options were to upgrade to an AR4 which was a huge investment and I was relying on selling my AR2 to fund it or to invest a couple of euro and see how it goes with an android HDMI stick.
In the end I used the free version of appradio unchained, spent €5 on the GPS Injector, €35 on the HDMI Dongle and I now have more features than the latest and greatest radio available. I like to mess about with technology so rooting the android dongle was a bit of fun and if it didnt work out I would use it for something else. It's not really that difficult to setup, in 1 hour you could have the whole thing running perfectly without any special expertise.
From the reviews I've read on the AR4 and carplay in general it doesn't seem all they've cracked it up to be with alot of bugs and stupid things showing up on the forum which really should have been fixed before releasing. I don't think I'd buy another Pioneer radio after the disasters they've made with all the AppRadios, from new radio releases each year to delays in releasing fixes, or in some cases not releasing fixes at all and just removing features.
They dont seem to be able to settle one format, is it AppRadio, AppRadio Live, AppRadio one or Carplay, it's getting ridiculous. the next year or two will be interesting to see where parrot go with their radio, and if apple allow more carplay compatable apps