So I have played with it some more:

I must say I dislike the hack around reading models (copying from assets to fs). I got burnt by forgetting to overwrite it more than once. My libtorch/JNI adaptation used torch::jit::load with string streams. This is less memory efficient, of course, but for development it is much more convenient. If it isn’t controversial, I could see if I file a PR.
One of the first things I needed was a method to get output pictures, I’ll file a PR for adding something like that to torchvision.
I hit a bug with some arm32 ops. Model works fine on Android/x86, colors/scanline widths are off on Android/arm(32). The net uses aten::_convolution, aten::add, aten::contiguous, aten::instance_norm, aten::reflection_pad2d, aten::relu_, aten::tanh, prim::Constant, prim::GetAttr, prim::ListConstruct with the most fancy convolutions being with stride=2 and a transposed one with stride=2 and output padding=1 (so no non-default dilations,  kernel 1,3,7). I’m still trying to narrow this down. As error looks like it is some “striding”/contiguous problem, I tried inserting lots of contiguous but it didn’t immediately help. I know this isn’t narrowed down enough yet, unfortunately.

Best regards
Thomas