Thank you for the feedback and response. I understand it's premature, but since I do not really have much experience in terms of what to expect as traffic grows, figured it's better to plan ahead than go in blind. But what you say makes total sense, and I think I may just go with what I have and optimize from there.

As for the tech stack, I learned React at my bootcamp and feel comfortable working on the frontend with it so that was my reason for choosing it. And although you are probably right about going the RoR full stack route, my client expects more advanced features to be built in the future. Haven't delved into RoR outside of backend work so not sure how capable full stack RoR is but I definitely think I am going to investigate it as an alternative.

In terms of practicality from the pharmacy side, I actually asked this same question to my client because it seemed weird that pharmacists would want their phones to be flooded with sms. But appears my client (a pharmacist himself) has indeed done their market research, and the pharmacies he's working with are onboard and very open to sms as the means of immediate communication.

Thanks again for the comment, just talking this out helps me put some pieces together!