I had the same problem of 3dcoat crashing immediately after I selected File > Import > Model for per pixel painting, I happen to be running on Fedora 39 and was using the 3dcoat-Ubuntu22.04 binary for 3DCoat-2023.40. I solved the problem by running 3dcoat in an Ubuntu 22.04 container using distrobox (see https://github.com/89luca89/distrobox ).  I expect this will enable 3dcoat to function fine on *any* modern linux distro that supports distrobox.  After you've installed distrobox:
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