Regarding the ovality and tolerances of the diameter of the wire (filament), I would ask you to check what are the deviation values ​​from the nominal 2.85mm, without jeopardizing the operation of the printer?

Ultimaker is an open filament. Which means you can use filament from any manufacturer.

For good and reliable operation of the machine, you need the following characteristics of the filament

Diameter 2.85mm

Allowed maximum tolerance ø 0.10mm

Ovality 95%