I would also like to get my hands on a Tech2 or a clone if such a thing actually works. But I am still trying to learn exactly what the Tech2 is. It seems like the go-to tool for a lot of things that I and others in my family with the same general year range of GM trucks and SUV's could use.
a tech 2 is what the dealers used to use. it basically did all the functionality stuff it could do. the dealer has moved on thou. it's out dated tech at this point. like mine won't read my 2014 volt, but it will read my 11 yukon.
the original ones were like 2k$ which was a lot back then, now eh.
the story I heard was like everything, the oem one was made in China like everything electronic is and when the factory moved on, they kept making them, with a software that worked without needing to be on the dealer wifi and log in but I believe they won't flash modules like the oem ones used to. but as a diagnostic tool, if you have something with a shop manual level of troubleshooting tree in it. the 300$ ones will run all those tests.
for example say you have a door lock that doesn't work with the switch, you go into the tech 2, command the door to lock. if it works you know it's the switch, if it doesn't you ruled that out and on to the next test.
I got mine from a link here. there's a long tech 2 thread. shipped from China directly. I think I've seen a post saying they don't sell them anymore thou. probably moved on to the newer harder you use laptop based but I believe it will flash modules and stuff. so I'll pick one of those up at some point too.