Q: Can I wear an apple watch on the inside of my wrist?

Hi

Apple Watch (including the built-in sensors) is designed to be worn on the top of your wrist:

Wearing your Apple Watch - Apple Support

Yes but see the following for some potential problems:

Can you use apple watch on the inside wrist?

It works fine but the heart rate is a tad bit less acurate

And you'll probably find that when you lift and turn your wrist to glance at the watch it won't automatically light. You'll have to tap the crystal.