Hello,
I just purchased a Tahoe 'High Country'. Has most of the 'bells and whistles'. I like the 'auto' running boards. A lot of 'digital' electronic stuff that I haven't learned the half of it. I will admit though I am disappointed about some of the 'hype' they talked about is not really available unless you pay for a subscription to 'OnStar'. GPS may be 'Google' but you will have to pay for it. I use my phone so can still 'navigate'. The one 'accessory' I don't have is the 'Hands free' ability. I would not use it if I had it but if one does have that ability you won't be able to use it unless you have an OnStar subscription. I do have the camera that can read road sign speed limits but it can't do it without an OnStar subscription. I wonder what other 'nice-i-ties' I can't use without OnStar? But, all in all I am satisfied with this vehicle. I am traveling on an extended mileage trip and with this 6.2L engine I am getting as much as 24-25mpg's. Yeah, that is quite astounding.....to me. But, you do have to use 'Premium' gasoline.....anywhere from 50 to 70 cents more a gallon. I did see that one of the posts indicated the GMC version will give you 3 years of OnStar? so you can utilize the 'bells and whistles'??? I have a 2021 Canyon Denali and I can't say it's 'premium' status is all that wonderful.
You are correct, that to use the included onboard apps, you need an active data connection...If you have ATT, you can add your vehicle to your cell phone plan for something like $10/month. If not, you have to get the data via onstar (although some have reported you can turn your phone into a hotspot, connect your infotainment system to it via wifi, and get data that way, but it is clunky at best). The "app access" plan which will give your infotainment system apps life from OnStar is $14.99/month ($180/year). FWIW, the old DVD based navigation systems update disk was around $300 and it came out annually...so $180/year to have up to date Google maps is a relative bargain...but agree, you can use CarPlay/Android Auto to get many of the same features via those platforms.
FYI, the camera does not read road signs, the dash and HUD speed limit sign display takes its info from the Google Maps...so if you don't have the data active, it doesn't work. Turn it off in the cluster settings if you are annoyed at seeing it blank.
This is the new GM strategy, subscription services...but you are correct, in the GMC's and Caddy's, you get 3 years of these services included in your purchase...helps justify the higher price tag. Used buyers are SOL...sometimes OnStar gives some free trials for used car buyers...check the web site.