I think it is more accurate than the Dexcom... but I never used the G7.

Found this about the G6

One explanation may be that something is pressing on your sensor which can affect your Dexcom G6 readings. Once the pressure is relieved, your Dexcom G6 readings should be closer to your blood glucose meter. Choose a sensor site location that won't be bumped, pushed, or laid on while sleeping.

My CGM is on the outside of my upper arm ( and I alternate arms when changing ). I tend to sleep on my side, which may explain the inaccuracy with the G6 ( and even sometimes with the Libre 3 )

I have even toyed with the idea of having one of each brand... But I'm sure my insurance won't cover both.

the accu-check unit needs QA/ programmed with each box/ bottle of glucose sticks. Neext add in lot number...

Or....

You could check with another glucosemeter/ finger stick...a friends maybe???

Also...

One could get a serum lab draw and also check glucose with the Dexcom when lab specimen is collected...then compare results with the outside lab results.