Just got my new Keteles K800 Dual Motor E-bike - Yolin Display Codes?

There are a couple other bikes that are essentially the same. The ZEEGR S1/SMLRO and the Philodo.
You can search for those models to gain additional insight. They all use two motors of 1kw and (typically) use the same display (in the current version). I think they all have a 48v 24.4 AH battery with a 50 Amp BMS. Some of the earlier versions did not have a rear suspension.

I have my wheels set to 29 inches, and they match my GPS for speed within 1/10th MPH.
Remember, your RIMS are 26 inches, but your fat tires add to the overall diameter.
This is why the default number used on most these bikes is 29 inches.
The Magicycle has a "26 Fat Tire' setting. I assume it is doing the math for the larger circumference, 26" tire.