Here are a few articles on the subject. Common among them is to try baking soda or non-gel toothpaste, both of which are mild abrasives, e.g.:

"...mix baking soda with water until a thick paste is formed. Apply a proper amount of paste to the scratch, gently rub along the stainless steel texture with a soft cloth or sponge, rinse and wipe dry."

• https://www.thisoldhouse.com/cleaning/22327722/removing-scratches-from-stainless-steel
• https://www.bobvila.com/articles/how-to-remove-scratches-from-stainless-steel/
• https://steelprogroup.com/stainless-steel/maintenance/scratches/

Thank you!

I'd first test those suggestions below in an inconspicuous area to make sure they don't make matters worse.

Two year olds are just so creative aren't they?