Hi. On the off chance you return here after two weeks, here's some help.
I hear you about the lack of zoom-in for really itsy-bitsy physics. Here's a straightforward solution, if you're willing to do a little extra work.
To utilize this for pixel-art scale, scale up the pixel-art graphics in your image editor (using Nearest Neighbor to keep the blockiness intact), and save the result as my_image_SCALED.png. Then import the scaled version into this and set your physics.
After editing, take your resulting code and add some changes like so:
physics_fixture_add_point(fix, xPos*image_xscale*my_rescale_multiplier , yPos*image_yscale*my_rescale_multiplier );
xPos/yPos is whatever number Fixture Editor provided. my_rescale_factor is whatever scale you used in your image editor (I'd use 8X or even 16X, personally, but whatever you use, if you're consistent about it, you can #macro my_rescale_multiplier).
In addition, as noted above, you will want to use a scalar for your Chain physics when implementing in the engine:
var offsetx = abs(sprite_width/2-sprite_xoffset);
var offsety = abs(sprite_height/2-sprite_yoffset);
physics_fixture_bind_ext(fix, id, 0-offsetx, 0-offsety);
That said, I have no idea if Keevee still supports this software, and all of my past attempts to get in touch have failed. Keevee, if you're still out there, please set the maximum-zoom level to low-enough for people to work on pixel-art natively, lol.