Hey, I downloaded the STL file and, using Blender with an add-on called “QRemeshify”, I converted it into a quad topology mesh.
Then I exported the model as OBJ and imported it into Moi3D using the SubD command.

I’m attaching the OBJ file below, so you have a model in Moi3D to work on that’s lighter than an STL file.

You can also find QRemeshify on GitHub, but maybe from this link (https://ksami.gumroad.com/l/QRemeshify) you get a version that works with the libraries as well.
However, if you’re dealing with this kind of file, you might want to consider Quad Remesher, which I already mentioned in my previous comment, because it produces a much better remesh.



Cheers

From any of your devasted images above you can have that!





Rodin or Tripo


Meshy


Krea 2


Here i take only one image (you can take 2 images in Krea)

Finally only Krea gives free models :) (from that i speedy test )

But heavy one and triangulated
So must use for example some quad decimater

This is impressive, really.
i can't wait to see the finished model