I’ve just submitted a Pull Request. It will likely not be available until Vassal 3.8.0. However, it could go into 3.7.x as it will not break anything, but of course older Vassal older than 3.7.x will not behave the same way wrt. limiting movement.
In the mean time, you can take a look at a custom class here. Compile the code in cholmcc and include it in your module. On maps where you want to be able to restrict movement, replace the VASSAL.build.module.map.PieceMover element with a cholmcc.PieceMover element.
Just to understand - do you want to use f.ex. a Dynamic Property trait to set whether a piece is selected, or do you want to be able to say if a piece can be selected - at all - via f.ex. a Dynamic Property trait?
The former can be achieve via similar changes to those made in the above PR. However, a bit of care need to be taken because the SELECTED property is treated a little different than other properties.
Yours,
Christian