Hehehe, I may know that …
There are a few GM extended range remote start kits still hanging around on eBay & Amazon. There’s also Clifford aka: viper that make one of the best if installed by a Pro.
www.gmtruckclub.com
The last and difficult to find option is the factory 3/4G factory OnStar module GM offered to 00-14 truck owners in Canada when 2G cell service was killed in ‘22.
Obviously they’re only available used, only from a wrecked 00-14 truck that had the Canadian o/s upgrade done and the wrecker bothers to part the vehicle out. They keep the skeleton of the original vehicle it was placed in and only the 2010+ modules are programmed for remote start via cell/OnStar.