Looking for ideas of the best way to get a ground in my shack when it’s on the second floor.

Is it an antenna ground?
Two story house or an apartment block?

For what reason are you grounding the shack? If it's for an electrical safety aspect then you already have an electrical ground. If it is for an RF ground I can go into a list of reasons why that is a bad idea from a electrical safety point of view on why you don't want to run your own ground system in parallel with the electrical mains ground, you can run into all sort of problems.

For a start, what sort of antenna system are you planning or using? That will have a bearing on if you need an RF ground or not.

never used one when i was three floors up no rf problem

I've dabbled on and off with earths for the shack. Never seems to make a difference to anything so I don't bother anymore.