From what I've heard and seen, they appear to be very easy to rack, which they ought to be considering that they are 9mm locked breach pistols.
That being said, I would recommend walking into your local gunshop and testing it out for yourself or whomever you're buying it for. If it's too heavy, the SIG P238 is a slightly smaller version of the same gun in .380 ACP which ought to be even easier to work the slide on.
If all else fails, look into one of the many firearms which are marketed with "easy-to-rack" as a feature like the S&W EZ9, SCCY CPX-2, Walther CCP, Remington R51, (supposedly the new R51s are reliable) etc.