PB at the local level is normally designed for the entire population of the municipality concerned. Anyone who would like to help shape things in their municipality can get involved.
Some PB processes are aimed at specific groups, such as women in the case of gender budgeting, or youth in the case of participatory budgeting for school students. While this kind of PB targets specific groups, other PB processes are designed for a highly heterogeneous target group. Some are even expressly aimed not only at the entire population of a city, but also more generally at anyone interested. The thinking behind this is that it is the idea that counts, rather than where a person comes from.