Don't mess around, send it to Keysight.
Why?
For the slow turn around? The way they wont deal with hobbyists?
If it's for the uncertainty then yes it's a wise choice but if it's not then just look at the 17025 accreditation and decide if it is ok for what you want to do.
Ask the lab for an example cert, do the same for Keysight and compare the two. See if what you will be getting fits your needs. A true voltnut will go in search of the lab that can give you the best and that might not be with the manufacturer.