Not sure that is strictly true. This is a national initiative, within the framework of the LOTG.
All football steps 5 and below will be using temporary Dismissals, therefore, I would expect that to extend to friendlies as the reporting of dissent cautions across the board upto step 5 has changed
If both teams involved in a non-competition game are step 5 or below then it would need to be used. Where both are step 4 or above it shouldn't be used. Where it is more complicated is a step 5 team playing a step 4 team, common sense there would suggest it isn't used as the step 4 team won't be using it.