I’m a special education teacher with ADHD. I have found that chewers are chewers tend to stay chewers and/or in need of some oral stimulation.
Hand fidgets are fine: there are special putties for sensory integration. Look for things on websites for Occupational Therapy as well as ADHD. Also, stress balls can be helpful and silent. You can get them at the same places or at the dollar store in the toy aisle. Fidget spinners are distracting to others and obnoxious.
I, too, will tend to chew on the inside of my cheek – which is not really a healthful idea. Instead try sugarless gum, candies or lozenges. That hits the oral fix without side effects unless you have TMJ. I also drink coffee with a straw and water from a sports bottle that has a cap that you suck the water through.
You may need to pick and choose when it is appropriate to use your figdets. With physical ones, if you can keep it under the table and not be obvious most other people don’t mind. With oral ones, just be quiet and keep your mouth closed.
I hope this helps,