Row-level Security to Multiple Reports with Same Dataset

Yes I did get it working as I wanted it to in the end although I found the help pages around this subject both confused and confusing at that time, maybe they are better now. As I recall I never was able to "test" the RLS with more than one report myself (which I think MS should fix, maybe they have now) -  so the "test" was publishing it and checking with some selected individuals that they could see what I expected them to see and only that. It seemed to work. I got around authentication probems by making the report available to everyone in my organisations domain (without notifying them) in a "premium workspace", but, then, restricting what any individual could see by using the RLS. The specific, but still, widely spread in the organisation, intended audience were then notified of their access as needed. If someone in the organisation gets a link but isn't in the RLS they see nothing or only the "bones" and textual content of the report. My RLS scheme itself was defined over several fields and it seemed to me that you can have as many fields defining RLS over a dataset as needed. My RLS related to one key field, if you have more than one key, probably that's more complex. So, yes, I think you can have different RLS on the same dataset in a hierarchy. Another level of control is provided by where and how you publish your report. If you have "Premium" workspaces then reports and apps are publishable to your entire organisation or any subset you can define (not RLS as such, but, can be used to the same effect). If not you are restricted to "Workspaces" and "Apps" which I think only those with a Pro license can see which is somewhat limiting. But, even with "Premium" you can choose to publish to a non-premium workspace if it suits your purpose to restrict access only to those with a Pro-License.