There is some speculation as to fidget spinners ameliorate nervous energy or psychological stress, but AFAIK there is no scientific basis for those claims.

That said, a largish keyring carrying useful trinkets can be spun on a finger if the need arises. Unlike the many spinners that can be found in the marketplace, a spinner can be assembled with lots of different useful items. It may not be as precisely balanced and effortless to keep spinning, but should be much more useful overall. YMMV