You could, but the head rush would be too intense. Nic salts were made for use in pod systems primarily, low wattage and high resistance devices.
This is not exactly true I'm afraid. Nic salts were MARKETED to pods as "nic salt capable" and there is no reason not to use them in ANY device, although certainly the higher the nic salt juice, the weaker the delivery system needs to be which is how Juul can get away with like, a pod concentration of up to almost 60 mg/ml.
They ARE smoother, they may or may NOT be more bioavailable depending on how they are converted, but they simply do not, in and off themselves "provide a special headrush" that is somehow confused with the headrush of ANY nicotine of the strength of 60 mg/ml. YOU WOULD FEEL it with any nic that strong.
Now, it's certainly debatable whether or not you could handle the HARSHNESS of freebase nic at that level, and it is true that some very high salt manufacturers WARN not to use oh, their 60 mg/ml juices in sub0hm systems, for one I imagine they don't want to be sued ,and for two, that is where the MARKET is for "Their' juices which tend to be very, very high.
However, if you DIY you can use nic salts and/or freebase plus nic salts in ANY device you see fit, provided you tailor the nic level to the device. The sub0hm user who habitually uses 6 m.g. can easily and with no care whatsoever transfer to a 6 mg/ml nic salt juice and come to ZERO harm and I am going to bet in the majority of cases, well, they won't get a magical "head rush" either as nic is nic is nic.
Sorry, pet peeve of mine, and factually completely untrue that nic salts are "best used in pods." Use them if you LIKE them, or if they have USE to you at the correct level and you should be Just fine.
I started DIY with nic salts at 18 mg/ml because I didn't want a throat hit. That was IT. Nic salts may be more stable chemically and also, they may store longer and also they can be formulated in different ways, by using citric, malic, and benzoic acids and I'd imagine each formulation may result in a slight different "salt" property i.e. one may be more bioavailable than the other, but this is speculation only. Also, the Juul is proprietary, so it's unclear what ALL is in their pods, but they do use benzoic acid and wonder if that contributes to the "head rush" experience but again, I don't know for sure.
Anna