It’s very situational and in terms of insurance and the local caa - probably not that grey.
perhaps If you shared with us more about what you want to achieve in your specific circumstance then it’ll be fairly easy to tell if you need to share costs
Now, you have a CPL.. You rent a Cessna and you take some passengers along. Are you still required to split the costs on equal basis? I've come to learn that there are still a lot of grey areas and in most cases you would need an AOC to operate. I couldn't really find a clear answer in the EASA Easy Access rules either. Any hot takes?
In this instance you need to operate under an AOC, you are hiring the plane and charging passengers to join you. If there's no AOC then you must cost share.
Now, it's possible they could hire the plane and pay you to fly it for them - however this needs to be well documented because should there be an accident and you didn't get it right, you and/or your estate would get a very large bill and potential prosecution.
Truly, the only surefire situation that you could be paid (with a CPL), or for free (with any licence). Is if someone hired you to fly the plane that they own personally whether there were passengers or not, so the owner of the aircraft is covering the costs and neither you nor the passengers pay a penny (with the exception of the costs of fuel)
The EASA "Easy Access Rules" are far from what the name implies.