Bare in mind that Scaling up an image would never be good... enough.
Having said that:
Image > Scale Image to your liking
Duplicate Layer
the top layer > Filters > Blur > Median Blur, around 5-7
Now, Bring the bottom layer above the one you blurred > Mode "Linear Light"
Right click on it > New from Visible > put this new layer in Mode "LCh Lightness"
Click on second layer > Duplicate > Mode "Luma Darken" or "Darken Only" (move it in the stack where you think it's best > play opacity)
Now you should have well blended pixels with sharp edges, but colors are off, at least it's a working base
Play with Opacity and visibility (the eye in front of layer) with the 3 upper layers, once you've mitigated between off colors and pixels > New from Visible > Filters > Hue Saturation > Adjust each colors independently (lightness/saturation/hue)
Then Filter > Enhance > Sharpen (Unsharp Mask)...
You can have a "map" of those those edges by putting the second layer in Mode " Difference" > then new from Visible > Put back the second layer in linear light > that new black layer put it on top of the stack and use it if you selecting the edges by selecting the black color > then invert, once selected tick the eye of that layer (no need anymore), you can use this selection in a mask (although I'll go with Threshold)
Having said that:
Image > Scale Image to your liking
Duplicate Layer
the top layer > Filters > Blur > Median Blur, around 5-7
Now, Bring the bottom layer above the one you blurred > Mode "Linear Light"
Right click on it > New from Visible > put this new layer in Mode "LCh Lightness"
Click on second layer > Duplicate > Mode "Luma Darken" or "Darken Only" (move it in the stack where you think it's best > play opacity)
Now you should have well blended pixels with sharp edges, but colors are off, at least it's a working base
Play with Opacity and visibility (the eye in front of layer) with the 3 upper layers, once you've mitigated between off colors and pixels > New from Visible > Filters > Hue Saturation > Adjust each colors independently (lightness/saturation/hue)
Then Filter > Enhance > Sharpen (Unsharp Mask)...
You can have a "map" of those those edges by putting the second layer in Mode " Difference" > then new from Visible > Put back the second layer in linear light > that new black layer put it on top of the stack and use it if you selecting the edges by selecting the black color > then invert, once selected tick the eye of that layer (no need anymore), you can use this selection in a mask (although I'll go with Threshold)