1. How do you access said apps? There has to be some repository storing the apps.
2. Certain regions can straight up ban sideloading by only allowing pre-approved app stores (eg. Mainland China). Ofc there will be technical ways to bypass this, but you are limited by technical knowhow and internal intelligence agencies abilities to find those people.
3. You could make using certain apps with such capabilities illegal. People may try to use it, but if found among a small set of protesters, they can just be "isolated". How do you prevent that?