Great help all - thanks!
I lost detail/added noise to my image with rasterize, so I may need to better learn about using that method. Doing a bit more digging related to everyone’s comments and learning more about the fill vs path issue helped me find the right answer.
Ultimately the steps I followed in illustrator to prepare my upload correctly were to:
Select all > Object > Flatten transparency (high res)
Object > Path > Outline Stroke
Thanks everyone for your help!
PS - along the way I came across this other thread that didn’t fully solve my issue, but I wanted to include here incase it helps anyone else coming across this issue. How do I engrave a path with stroke but no fill?