I don’t know a lot about the rest of Europe on this, but here in France it’s been more than a decade SMS are unlimited in mobile plans, and these plans are quite cheap.
I have the same issue and it's driving me crazy. One bluetooth device is waking up a MBP M4 regularly during the night, lighting up an external screen. Even without any connected devices.
We also migrated away from Next.js last year to [Vike], big improvment on developer experience all around. Most of our needs are covered by just pre-rendering pages ([SSG])
We had separate database and app instances, the DB instance had 32 cores and 64GB memory, which we doubled to keep up with our requirements. We have tens of millions of visits daily, and our database was close to ~300GB within the first few months.
For plausible I believe that since it runs on Postgres, scaling should not be a problem as long as you scale the resources with it.