I'll add a little more detail on why based on my gen 1 experience I hope gen 2 is also offered via REI:
After purchasing my gen 1 Adventurer at REI, I right away noticed into an issue with altitude not recording accurately. After troubleshooting with Garmin support we determined it was probably a hardware/barometer problem.
Luckily I was still within the 90-days no hassle return period for REI and I simply swapped it for a brand new unit. And that one worked perfectly :-)
So REI offers a super easy and stress free way to purchase an expensive item like this and rest assured that if there are any problems you can easily return/replace for a new unit.
I love REI too. The REI official webpage shows the MARQ (Gen 2) Athlete as a new arrival. REI might be able to provide you with more information on whether the MARQ (Gen 2) series will be online limited or in their stores too at some point.