What's to stop people from buying the least powerful 2.7 and hopping it up via laptop? Are there actual physical differences in the engines or not?
General Motors is there to stop people from doing this.
Modern General Motors ECMs are locked down tighter than Fort Knox.
E90 ECM on the L84 5.3L and L87 6.2L and E41 ECM on the L5P Duramax require removing the ECM and sending it off for hardware changes, starting at $700, before you can start tuning on it. These are on Global A vehicles. With no reasonable solution for getting inside the ECM to tune, in-line pedal tuners like the Banks Pedal Monster (for the Duramax) and Pulsar (for the gas engines) have become popular again.
ECMs on GM's VIP electrical architecture have been an even more difficult beast. As it stands now, nobody has a commercial solution for getting into the E99 ECM used on the C8. The aftermarket has taken to adding piggyback ECUs to support performance modifications.
Not sure what electrical architecture the Colorado will use. Full size trucks changed from Global A to VIP with the 2022 refresh. If the new Colorado uses Global A, tuning may be possible, but prohibitively expensive and a massive PITA. If it is VIP, it'll be straight up impossible for the foreseeable future and possibly forever.
Of course, then you have to get past GM knowing someone had their greasy fingers in the calibration files and sticking a warranty block on your VIN.