These are satisfying, but will get dirty fast. I think they can go through the washer but not a dryer: https://www.amazon.com/dp/B078M7BTDL/ref=cm_sw_r_cp_apa_fabc_XN41PFVHPQ204BK93H5Z

I've also made a stress ball using a deflated balloon filled with flour. There's tutorials online. I have had them blow up on me and get flour everywhere when I haven't done them right, but only at first when I was going through trial and error. I've also thought about filling them with water beads for a less messy effect.

Also fond of these hand strengthening balls. I bought mine at target, but these appear to be similar if not the same. They are very bouncy, though, but easy to wash off if dropped and won't get dirty like those squishies. https://www.amazon.com/dp/B00525X8KW/ref=cm_sw_r_cp_apa_fabc_D89DZQECVYYXTQWF63YY

Then there's tons of fidget jewelry out there that are subtle. I have a necklace. I've eyed up rings, too. Also eyeing up a flatter hand fidget device similar to a fidget cube.