Wow...lots of updates in one day on this... and to be honest, I don't want to be editing multiple quotes... so just look for your section, previous posters...LOL
To the OP - you're getting some good info here from everyone.
I'll echo the 'get a HU that has Android Auto built in'. My Pioneer HU doesn't have the AA compatibility (it supposedly can work with Apple CarPlay, but I will never be a follower of St. Steve of Cupertino); it does have a free Pioneer app that is supposed to put the Android phone's screen on the HU screen, but I never got it to work right. I have a unit similar to Matt's, but mine has HD Radio and Spotify built in. It also has *two* video outputs (so you can hook up a backup camera, and still play DVDs to your passengers, a USB *and* 3.5mm Aux input (which are in the back, but I put in an adapter cable that runs to where my cigar lighter used to be, and the USB and Aux are right there in the front - looks factory.
Why do I mention this? Because the OP is about to send off to China and pay more $ than Matt and I did. That Pioneer cost me $160 and change from Sonic Electronix online. Nice thing was, I could demo it at my local BestNotBuy, so I knew what I was getting beforehand. Try that with China. (no, I'm not dogging the OP...just pointing out there are other options)
On Android Auto - I upgraded my phone a few months back because my Accord has it as standard equipment - and it is *really* nice. It's kind of like having Google Home...but in your car. Want to find some info while you're on the road? Press the talk button and ask Google. Did you have a song pop in your head, and would like to hear it, but don't have it in the car / phone? If you have a Spotify sub (or perhaps a Pandora will work also,) tell Google to play it, and it's coming to you via Spotify a few seconds later. As someone else pointed out...AA will show Google Maps on your screen, if you have a display screen - so I fully agree with the previous poster who said 'no more NAV HUs for me'
Also - I believe the new (or about to be new - electronics mfgs tend to release updated product in March-April) Pioneers now have the AA built-in !
Spotify vs. SiriusXM - Spotify for the win, IMO. I used to be a subscriber to SXM practically since they came out (I had one of those 1st-gen Sony units, even...later a Pioneer Inno, so I could record the content). But since Sirius purchased XM and took them over, their sound quality decreased, and their content became crappier, IMO. (XM always had way better SQ than Sirius)
XM, to me, was a really good thing before Sirius messed it up. Plus they stopped selling 'lifetime subs'. Anyway... Once Spotify became available, and I found out it's features / cost... to Mooseman's point, it is *way* more flexible, and *half* the price of XM ($10/mo USD for Spotify premium.) And I can tailor it exactly to what I want at home (my Roku even has it!), and then that follows me in the car, or on any device I have that has Spotify on it. You can download it *to* the device(s), as well, as Moose pointed out - then you don't even need a network connection to play it. SXM...well, they have a lot of channels, but half of them I would never listen to - and the music is a lot more homogenized than it was on XM alone. You can figure out easily what I spent on XM / SXM over the past 20yrs or so...now there are better options available, IMO. You can also get podcasts, etc. w/ Spotify. Not sure about audiobooks, but there's another app for that, so...
Someone mentioned XM in large cities w/ tall buildings... XM actually had a terrestrial repeater network in cities like these - so you could still listen downtown, etc. I don't know if they still have that, but if they do, I can't imagine downtown Denver not having it. I'd still go w/ Spotify, though... cellular signal is almost pervasive, and it won't have very many dropouts, if you have a good phone / good carrier.
Sounds like the OP wants to listen to terrestrial radio...I still listen to it, too, so I understand. If that's important to you, you want to look at FM capture ratio, especially, and lower numbers in this stat are better. Alpine used to have really good FM reception (I haven't had one of their units in awhile, though). My current Pioneer is good. Before that, I had a Kenwood - actually one of their upper-tier Excelons - and the tuner wasn't as good as the one I have in the Pioneer. The HD Radio holds capture better in the Pioneer vs the Kenwood, too. A good source of comparing tuner stats for many radios at once is Crutchfield (but their prices are high, compared to other sites.)
Back to the SWC, which seems to be important to our OP... if you're going to try the GMOS-04, they give you the subharness with it, to connect their add-on SWC box to the main GMOS box - again...plug & play, it controls the SWC through the GMOS harnesses, and no cutting of the GM wiring needed.
Ok - I think that covers everything since my last post. Happy Shopping!