many of these things have documented methods of subversion, so im not gonna talk about dots (take the yellow out, also theres some special programs u can use to add hella dots) or other shit, cause its simple but technical.
I've basically stopped giving a shit if the gov knows my politics. I'm not a terrorist. I'm a class enemy. At some point of u have to accept some risk. I dont use social media so its not like i'm out there liking agitprop on facebook, but i've had my share of horrible practices in the past if totally hiding your political inclinations is the goal.
It's a good goal to leave as little data behind as possible obviously, but i dont think feds are analyzing pics for messages, and if they are its just an automated thing so ur not costing them anything… in fact if they have any success or ability to say "we have x amount of steganographic photos" they'll get their budget renewed or increased so meh.
We gotta not act like terrorists. There are times to hide information, and there are times when the cost of hiding information outweighs the cost of leaking it (e.g. the info you have to leak by joining an org).
Digital propaganda is probably not very dangerous. In any case, the pigs can assassinate you for even having a bad vibe about you, the only answer to this is social (squad up, stay strapped, educate people on this, etc.) and not technical, as much as a technofix would be very nice (and for many things there are good technofixes with cryptography and mixnets, for example, im not catagorically against any of this im really into it, just deep enough to know that u cant cover everything, and some time u have to weight the pros and cons, and in a realistic way not a paranoid worst case way)