Does Retrobatch have a 1-bit-color output option? The one that Photoshop calls “bitmap” – each pixel either black or white, no grayscale in between?
To be specific: Grayscale images with a threshold or a matching color profile won’t do the job. Those look like 1-bit, but technically still are 8-bit (or more) will get rasterized when processed for print, resulting in jaggy lines.
Adobe handles 1-bit-images separately and offers higher resolution and different compression for PDF embedding. Without getting into politics here, I’m looking into Adobe alternatives, and the Affinity suite completely lacks 1-bit-color support, even as an export option.