Galloway
The short answer to your short question is No. Steaming dents doesn’t work well thru Varnish. Also, Uberti also applies a “filler” which further tends to seal out moisture. You will need to strip the stock, steam out the dents, refinish.
Forgot. If you are just dealing with dents in the varnish only, varnish needs sanded down then reapplied. If you go past the clear coat, you will need to completely strip and refinish as matching Uberti filler and color will be near impossible.