Judge this by one word in the sources: appearance. Cleveland Clinic speaks about how stretch marks look, and that is the claim to hold the treatment to.
What the source says
Cleveland Clinic says microneedling "can minimize stretch marks, scars, wrinkles and other skin concerns."
The same source adds that the procedure "can help reduce the appearance of skin concerns such as acne scars, stretch marks or wrinkles."
In plain words, the sources name stretch marks as one concern microneedling can reduce. The verbs are "minimize" and "reduce the appearance." Both describe a change in how the marks look.
Scars share the same sentence
Both lines list acne scars next to stretch marks. If scar treatment is what you are really weighing, the PMC review of acne scar pathogenesis, classification and treatment is a place to start reading.
Microneedling in other settings
Microneedling also appears in research on other concerns, such as this comparison of PRP with PRP microneedling in androgenetic alopecia. That paper is about hair loss, so it does not speak to stretch marks.
Asking the provider about your stretch marks
Ask the provider to explain, in their own words, what microneedling can do for your stretch marks. Then hold their answer against the Cleveland Clinic wording above.