Somewhere other than a Drobo / NAS, they’ll work, they’re fine when used in a desktop PC as intended, or singly as external drives.
I would NOT use them in any sort of RAID though, especially not one with data on, they might appear to work, the worst problem comes when you replace a drive, during the rebuild process they run out of fast cache, slow right down, often get marked as failed, & then the entire rebuild fails… meaning all data gets lost at that point.
Can’t tell anything about the unit while it has SMR drives fitted, two CMR IronWolf drives should do to set it up though, more can be added later to expand &/or enable dual redundancy, something I’d actually recommend doing with drives of 4TB or greater once you have enough of them. You should only need 2 drives to set it up with single redundancy, dual can be enabled once you have 3 or more without losing data.
In ordinary times where units were in stock I’d suggest just proceeding with IronWolf or similar CMR NAS rated drives, since if the unit was problematic you could get another & move the pack without data loss.
In the current “no stock anywhere” situation, it’s up to you if you want to take the risk or simply start off with a competitor’s unit. Whatever you decide I wouldn’t recommend SMR drives in any sort of NAS though.