SDR?

Software Defined Radio.

Are they really broadcasting the imagery back down from the satellite without encryption?

I should have specified, I was referring to the NOAA ones that are public

These images are super far away though eg. entire Earth so idk

I will add for the U.S. based satellites the disc images are from the NOAA GOES sats which are in a Geosynchronous orbit but there is also the NOAA-15/18/19 which are lower in a Sun-synchronous orbit and you get a strip as it passes over.

They're publicly funded public data. But the images are mostly only useful for tracking cloud cover.

I have to guess that a lot of the sales are things like "please look at this specific plot of land once a week" or something way cheaper than having someone go take pics or something.

Like if your job is to make a bunch of money predicting crop futures you could probably justify spending.... $10k/year on pictures I bet? Though you gotta be careful with this kind of reasoning and not double-count your profits. And like all of this kind of stuff I bet that Maxar lives off of people with inflated budgets being able to ask for stuff.