Good luck with dispersed camping in the US east of the Mississippi (or for that matter, in Texas). It is totally reliant on federal public land, which essentially exists only in the western states. Out east [0], or in Texas, you will find yourself in a situation much more similar to the one in France (or England, or Germany, or ...)
[0] and effectively, the east/west boundary is not even the Mississippi, but something like the 101st meridian. Dispersed camping in eastern Kansas is next-to-impossible.
You do have federal and state lands in the eastern US but, of course, nothing like the vast tracts out west. In any case, with the notable exception of the Appalachian Trail, there are fewer options for long-distance backpacking in the east though there are some hut systems and, subject to various rules, you can find places to camp in national forests in particular.
I grew up in the area and camped many times with friends in high school and college by just walking a few miles down a trail and then moving off the trail a bit. I believe back then the primitive camping limit was 90 days per spot. The Rainbow People used to push that to the max when they moved through the area.
I live in New England now and other than some remote state parks here in Massachusetts there isn't any primitive camping so you are right about far east of the Mississippi.
For comparison in the US dispersed camping usually just has very general rules like can't stay in an area more than 30-60 days, have to leave no trace, respect fire bans, and deal with other local restrictions like on hunting, foraging, fire wood collecting, etc.