Typically drastically smaller than that.
Using a serial enabled LoRaWan unit and feed the data over serial would be much easier.
That’s still mischaracertizing it.
You can’t put a serial stream through LoRaWan; what you can do is have something that truly understands the limitations of LoRaWan (both the uniform ones, and the contextual ones that depend on the currently needed spreading factor), which hands off suitable packet payloads at contextually appropriate times to a LoRaWan stack.
That handoff can indeed be accomplished over a serial UART, as many of the AT-command solutions do.
But it’s a serious mistake and misrepresentation to imply that there does or even can exist any LoRaWan box into which it is appropriate to feed generic serial data. Even if the source data size and rate is appropriate, it’s still unwise to have the flow not be contingent on the current state of the LoRaWan protocol.
Serial interfaced LoRaWan stacks are sensible and common; but serial to LoRaWan bridges cannot meaningfully exist - that’s like trying to make a car that folds into a backpack.
(not that misrepresentation of fundamental facts ever stopped a manufacturer’s advertising department…)