You do NOT have to use a tech2Oh, I have, trust me. 2008 Chevy Cobalt, definitely needs the TechII.
I had a Matco Maximus 2.0 that did all gm key fobs
Also have a currently versus edge that does it
But most lock Smith’s good ones has the software to do same
The old gm Keys you can do it without a scan tool
Like old fords too
If you was closer I’ll be glad help with my scanner
I just did a 16 Gmc key fob for my neighbor