The reason it prints correctly in Inkscape is because it has physical dimensions, when you save an image it is stored as pixels (sometimes with an embedded DPI which can be used to translate back to the physical size, which is what T2Laser does if you enable that option - not recommended).
T2Laser / Grbl uses metric units, so a DPI of 254 = 10 DPmm = Resolution of 0.1mm.
If you are using 0.2 resolution then save the image at 127 DPI and it will load the correct size. If this isn't working as expected then the problem is with the export from Inkscape, load the image back to Inkscape or another image viewer and check the pixel count.
Since you are going to trace these you could also do that in Inkscape and save a DXF, this format uses physical dimensions (mm) and doesn't rely on scaling.