"So" refers to the result produced according to the conditions, which may be the result you need or the premise that indirectly leads to the next result. In order to visually show the result you want (or the next result of the topic), the term "namely" is used.
Usually "namely" uses simple transformation, so that the result of "so" leads to the next step or subsequent step more appropriately, so as to keep the whole process logical and rigorous and easy for readers or commentators to understand.
Please analyze and test the specific use according to the specific problems.