I recently acquired a great truck gun. A Kel-Tec Sub 2K that uses Glock 17 mags. I have zero experience with Glocks. So, I would like to get a Glock Sub compact for carry that could share mags with the Sub 2K and am looking for some suggestions.
For the Sub2K, you might think about getting the 33-round Glock mags (which, I'll note, will ALSO fit into Glock pistols). Brownells and Botach normally have them in stock.
As has been said, the G17, G19, and G26 are the guns (in full-size, compact, and sub-compact, respectively) that will all take the same G17 magazines (and the 33-round G18 mags, too).
Many people that I know REALLY prefer the grip on the Gen 4 versions. (And yes, both the Gen 3 and Gen 4 versions will take all the mags.)
I note you don't HAVE to use a subcompact for carry unless you really want to. I know a number of people who carry the G17 daily, and TONS of people carry the G19 (probably one of the most popular carry guns out there). That being said, the G26 is easy to shoot well, and has a 10+1 capacity with its standard magazine, and you can reload to a G17 magazine with no issue.