How to give snaps access to /somedir

Recently I stumbled about not being able to give chromium access to a specific folder. I learned much about snap but really got frustrated and gave up. In the end I did it the non snap way, which is sad IMHO. So I am impressed of the snap universum and can imagine what work is behind but somehow a higher abstract user layer is missing for sure. I am sitting here with Ubuntu 20.04 and I am lost with snaps, interfaces, connections, plugs. So I am probably not the mom using a browser, I am also not a nerd programming snap, I am somewhere between able to handle Linux. So I am asking the above question? I can understand this implies a lot of steps to be done but is it possible anyway?

Simply for the records I found this discussion here, but also this does not contain a real answer.